diff --git a/src/main/java/com/ffii/tsms/modules/data/entity/CustomerContactRepository.java b/src/main/java/com/ffii/tsms/modules/data/entity/CustomerContactRepository.java
index 781d6fd..b1b11da 100644
--- a/src/main/java/com/ffii/tsms/modules/data/entity/CustomerContactRepository.java
+++ b/src/main/java/com/ffii/tsms/modules/data/entity/CustomerContactRepository.java
@@ -1,7 +1,11 @@
 package com.ffii.tsms.modules.data.entity;
 
 import com.ffii.core.support.AbstractRepository;
+import org.springframework.data.repository.query.Param;
+
+import java.util.List;
 
 public interface CustomerContactRepository extends AbstractRepository<CustomerContact, Long> {
 
+    List<CustomerContact> findAllByCustomerId(@Param("customerId") Long customerId);
 }
\ No newline at end of file
diff --git a/src/main/java/com/ffii/tsms/modules/data/entity/CustomerRepository.java b/src/main/java/com/ffii/tsms/modules/data/entity/CustomerRepository.java
index aaab530..a83a25b 100644
--- a/src/main/java/com/ffii/tsms/modules/data/entity/CustomerRepository.java
+++ b/src/main/java/com/ffii/tsms/modules/data/entity/CustomerRepository.java
@@ -1,9 +1,13 @@
 package com.ffii.tsms.modules.data.entity;
 
 import java.util.Optional;
+import java.util.List;
+
+import org.springframework.data.repository.query.Param;
 
 import com.ffii.core.support.AbstractRepository;
 
 public interface CustomerRepository extends AbstractRepository<Customer, Long> {
     
+    Optional<Customer> findByCode(@Param("code") String code);
 }
\ No newline at end of file
diff --git a/src/main/java/com/ffii/tsms/modules/data/service/CustomerContactService.kt b/src/main/java/com/ffii/tsms/modules/data/service/CustomerContactService.kt
new file mode 100644
index 0000000..72bc9a8
--- /dev/null
+++ b/src/main/java/com/ffii/tsms/modules/data/service/CustomerContactService.kt
@@ -0,0 +1,43 @@
+package com.ffii.tsms.modules.data.service
+
+import com.ffii.tsms.modules.data.entity.CustomerContact
+import com.ffii.tsms.modules.data.entity.CustomerContactRepository
+import com.ffii.tsms.modules.data.entity.CustomerRepository
+import org.springframework.stereotype.Service
+
+@Service
+class CustomerContactService(
+    private val customerContactRepository: CustomerContactRepository,
+    private val customerRepository: CustomerRepository
+) {
+
+    fun findAllByCustomerId(customerId: Long): List<CustomerContact> {
+        return customerContactRepository.findAllByCustomerId(customerId)
+    }
+
+    fun saveContactsByCustomer(saveCustomerId: Long, saveCustomerContact: List<CustomerContact>) {
+
+        val customerContactList = mutableListOf<CustomerContact>()
+
+        val customerContactSize = saveCustomerContact.size
+
+        for (i in 0 until customerContactSize) {
+            val customer = customerRepository.findById(saveCustomerId).orElseThrow()
+            val customerContact = CustomerContact().apply {
+                id = if(saveCustomerContact[i].id!! > 0) saveCustomerContact[i].id else null
+                this.customer = customer
+                name = saveCustomerContact[i].name
+                phone = saveCustomerContact[i].phone
+                email = saveCustomerContact[i].email
+            }
+
+            customerContactList.add(customerContact)
+        }
+
+        customerContactRepository.saveAll(customerContactList)
+    }
+
+    fun deleteContactsByCustomer(deleteContactIds: List<Long>) {
+        customerContactRepository.deleteAllById(deleteContactIds.filter { it > 0 })
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/ffii/tsms/modules/data/service/CustomerService.kt b/src/main/java/com/ffii/tsms/modules/data/service/CustomerService.kt
index 31dfc5a..f916a93 100644
--- a/src/main/java/com/ffii/tsms/modules/data/service/CustomerService.kt
+++ b/src/main/java/com/ffii/tsms/modules/data/service/CustomerService.kt
@@ -1,14 +1,22 @@
 package com.ffii.tsms.modules.data.service
 
 import com.ffii.tsms.modules.data.entity.Customer
+import com.ffii.tsms.modules.data.entity.CustomerContact
 import com.ffii.tsms.modules.data.entity.CustomerType
 import com.ffii.tsms.modules.data.entity.CustomerRepository
 import com.ffii.tsms.modules.data.entity.CustomerTypeRepository
+import com.ffii.tsms.modules.data.web.models.NewCustomerResponse
 import com.ffii.tsms.modules.project.web.models.SaveCustomerRequest
 import org.springframework.stereotype.Service
+import java.util.Optional
 
 @Service
-class CustomerService(private val customerRepository: CustomerRepository, private val customerTypeRepository: CustomerTypeRepository, private val customerSubsidiaryService: CustomerSubsidiaryService) {
+class CustomerService(
+    private val customerRepository: CustomerRepository,
+    private val customerTypeRepository: CustomerTypeRepository,
+    private val customerSubsidiaryService: CustomerSubsidiaryService,
+    private val customerContactService: CustomerContactService,
+) {
 
     fun allCustomers(): List<Customer> {
         return customerRepository.findAll()
@@ -17,41 +25,63 @@ class CustomerService(private val customerRepository: CustomerRepository, privat
     fun allCustomerTypes(): List<CustomerType> {
         return customerTypeRepository.findAll()
     }
-    
+
     fun findCustomer(id: Long): Customer {
         return customerRepository.findById(id).orElseThrow()
     }
 
-    fun saveCustomer(saveCustomer: SaveCustomerRequest): Customer {
+    fun findCustomerByCode(code: String): Optional<Customer> {
+        return customerRepository.findByCode(code);
+    }
+
+    fun saveCustomer(saveCustomer: SaveCustomerRequest): NewCustomerResponse {
+
+        val duplicateCustomer = findCustomerByCode(saveCustomer.code)
+
+        //TODO: check duplicate customer
+        if (duplicateCustomer.isPresent()) {
+            return NewCustomerResponse(
+                customer = duplicateCustomer.get(),
+                message = "The customer code has already existed"
+            );
+        }
 
         val customerType = customerTypeRepository.findById(saveCustomer.typeId).orElseThrow()
 
         val customer =
-                customerRepository.saveAndFlush(
-                        Customer().apply {
-                            id = saveCustomer.id
-                            code = saveCustomer.code
-                            name = saveCustomer.name
-                            this.customerType = customerType
-                            address = saveCustomer.address
-                            district = saveCustomer.district
-                            brNo = saveCustomer.brNo
-                        }
-                )
+            customerRepository.saveAndFlush(
+                Customer().apply {
+                    id = saveCustomer.id
+                    code = saveCustomer.code
+                    name = saveCustomer.name
+                    this.customerType = customerType
+                    address = saveCustomer.address
+                    district = saveCustomer.district
+                    brNo = saveCustomer.brNo
+                }
+            )
 
         val customerId = customer.id
-        
+
         if (customerId != null && customerId > 0) {
 
-            if (saveCustomer.deleteSubsidiaryIds.size > 0) {
+            if (saveCustomer.deleteSubsidiaryIds.isNotEmpty()) {
                 customerSubsidiaryService.deleteSubsidiariesByCustomer(customerId, saveCustomer.deleteSubsidiaryIds)
             }
 
-            if (saveCustomer.addSubsidiaryIds.size > 0) {
+            if (saveCustomer.addSubsidiaryIds.isNotEmpty()) {
                 customerSubsidiaryService.saveSubsidiariesByCustomer(customerId, saveCustomer.addSubsidiaryIds)
             }
+
+            if (saveCustomer.deleteContactIds.isNotEmpty()) {
+                customerContactService.deleteContactsByCustomer( saveCustomer.deleteContactIds)
+            }
+
+            if (saveCustomer.addContacts.isNotEmpty()) {
+                customerContactService.saveContactsByCustomer(customerId, saveCustomer.addContacts)
+            }
         }
-        
-        return customer
+
+        return NewCustomerResponse(customer = customer, message = "Success");
     }
 }
diff --git a/src/main/java/com/ffii/tsms/modules/data/service/CustomerSubsidiaryService.kt b/src/main/java/com/ffii/tsms/modules/data/service/CustomerSubsidiaryService.kt
index 6e5b217..757cab2 100644
--- a/src/main/java/com/ffii/tsms/modules/data/service/CustomerSubsidiaryService.kt
+++ b/src/main/java/com/ffii/tsms/modules/data/service/CustomerSubsidiaryService.kt
@@ -18,12 +18,15 @@ class CustomerSubsidiaryService(
         return customerSubsidiaryRepository.findAll()
     }
 
+    fun findAllByCustomerId(customerId : Long) : List<CustomerSubsidiary> {
+        return customerSubsidiaryRepository.findAllByCustomerId(customerId)
+    }
     fun findAllSubsidiaryIdsByCustomerId(customerId : Long) : List<Long> {
 
         val customerSubsidiaryList: List<CustomerSubsidiary> = customerSubsidiaryRepository.findAllByCustomerId(customerId)
 
-        if (customerSubsidiaryList.size > 0) {
-            return customerSubsidiaryList.map { it.subsidiary.id }.filterNotNull()
+        if (customerSubsidiaryList.isNotEmpty()) {
+            return customerSubsidiaryList.mapNotNull { it.subsidiary.id }
         } else return emptyList()
     }
 
@@ -49,19 +52,12 @@ class CustomerSubsidiaryService(
 
     fun deleteSubsidiariesByCustomer(deleteCustomerId: Long, deleteSubsidiaryIds: List<Long>) {
 
-        val customerSubsidiaryList = mutableListOf<CustomerSubsidiary>()
-
-        val subsidiaryIdsSize = deleteSubsidiaryIds.size
-
-        for (i in 0 until subsidiaryIdsSize) {
-            val customer = customerRepository.findById(deleteCustomerId).orElseThrow()
-            val subsidiary = subsidiaryRepository.findById(deleteSubsidiaryIds[i]).orElseThrow()
-            val customerSubsidiary = CustomerSubsidiary().apply { 
-                this.customer = customer
-                this.subsidiary = subsidiary
-            }
+        val customerSubsidiaryList: List<CustomerSubsidiary> = findAllByCustomerId(deleteCustomerId)
 
-            customerSubsidiaryList.add(customerSubsidiary)
+        if (customerSubsidiaryList.isNotEmpty()) {
+            val filteredSubsidiaryIds: List<Long> =
+                customerSubsidiaryList.filter { deleteSubsidiaryIds.contains(it.subsidiary.id!!) }.mapNotNull { it.id }
+            customerSubsidiaryRepository.deleteAllById(filteredSubsidiaryIds)
         }
     }
 }
diff --git a/src/main/java/com/ffii/tsms/modules/data/web/CustomerController.kt b/src/main/java/com/ffii/tsms/modules/data/web/CustomerController.kt
index 6ae5780..e7072f6 100644
--- a/src/main/java/com/ffii/tsms/modules/data/web/CustomerController.kt
+++ b/src/main/java/com/ffii/tsms/modules/data/web/CustomerController.kt
@@ -4,8 +4,9 @@ import com.ffii.tsms.modules.data.entity.Customer
 import com.ffii.tsms.modules.data.entity.CustomerType
 import com.ffii.tsms.modules.data.service.CustomerService
 import com.ffii.tsms.modules.data.service.CustomerSubsidiaryService
+import com.ffii.tsms.modules.data.web.models.CustomerResponse
+import com.ffii.tsms.modules.data.web.models.NewCustomerResponse
 import com.ffii.tsms.modules.project.web.models.SaveCustomerRequest
-import com.ffii.tsms.modules.project.web.models.CustomerResponse
 import org.springframework.web.bind.annotation.GetMapping
 import org.springframework.web.bind.annotation.RequestMapping
 import org.springframework.web.bind.annotation.RestController
@@ -37,7 +38,7 @@ class CustomerController(private val customerService: CustomerService, private v
     }
 
     @PostMapping("/save")
-    fun saveCustomer(@Valid @RequestBody saveCustomer: SaveCustomerRequest): Customer {
+    fun saveCustomer(@Valid @RequestBody saveCustomer: SaveCustomerRequest): NewCustomerResponse {
         return customerService.saveCustomer(saveCustomer)
     }
 }
\ No newline at end of file
diff --git a/src/main/java/com/ffii/tsms/modules/data/web/CustomerSubsidiaryController.kt b/src/main/java/com/ffii/tsms/modules/data/web/CustomerSubsidiaryController.kt
index 85564b2..f24436f 100644
--- a/src/main/java/com/ffii/tsms/modules/data/web/CustomerSubsidiaryController.kt
+++ b/src/main/java/com/ffii/tsms/modules/data/web/CustomerSubsidiaryController.kt
@@ -5,7 +5,7 @@ import com.ffii.tsms.modules.data.entity.CustomerSubsidiary
 import com.ffii.tsms.modules.data.service.CustomerService
 import com.ffii.tsms.modules.data.service.CustomerSubsidiaryService
 import com.ffii.tsms.modules.project.web.models.SaveCustomerRequest
-import com.ffii.tsms.modules.project.web.models.CustomerResponse
+import com.ffii.tsms.modules.data.web.models.CustomerResponse
 import org.springframework.web.bind.annotation.GetMapping
 import org.springframework.web.bind.annotation.RequestMapping
 import org.springframework.web.bind.annotation.RestController
diff --git a/src/main/java/com/ffii/tsms/modules/data/web/models/CustomerResponse.kt b/src/main/java/com/ffii/tsms/modules/data/web/models/CustomerResponse.kt
index fee567e..1317cd0 100644
--- a/src/main/java/com/ffii/tsms/modules/data/web/models/CustomerResponse.kt
+++ b/src/main/java/com/ffii/tsms/modules/data/web/models/CustomerResponse.kt
@@ -1,8 +1,9 @@
-package com.ffii.tsms.modules.project.web.models
+package com.ffii.tsms.modules.data.web.models
 
 import com.ffii.tsms.modules.data.entity.Customer
 
 data class CustomerResponse(
     val customer: Customer,
     val subsidiaryIds: List<Long>,
-)
\ No newline at end of file
+)
+
diff --git a/src/main/java/com/ffii/tsms/modules/data/web/models/NewCustomerResponse.kt b/src/main/java/com/ffii/tsms/modules/data/web/models/NewCustomerResponse.kt
new file mode 100644
index 0000000..ae36f2b
--- /dev/null
+++ b/src/main/java/com/ffii/tsms/modules/data/web/models/NewCustomerResponse.kt
@@ -0,0 +1,8 @@
+package com.ffii.tsms.modules.data.web.models
+
+import com.ffii.tsms.modules.data.entity.Customer
+
+data class NewCustomerResponse (
+    val customer: Customer,
+    val message: String,
+)
\ No newline at end of file
diff --git a/src/main/java/com/ffii/tsms/modules/data/web/models/SaveCustomerRequest.kt b/src/main/java/com/ffii/tsms/modules/data/web/models/SaveCustomerRequest.kt
index 2b4f4ff..620109c 100644
--- a/src/main/java/com/ffii/tsms/modules/data/web/models/SaveCustomerRequest.kt
+++ b/src/main/java/com/ffii/tsms/modules/data/web/models/SaveCustomerRequest.kt
@@ -1,5 +1,6 @@
 package com.ffii.tsms.modules.project.web.models
 
+import com.ffii.tsms.modules.data.entity.CustomerContact
 import jakarta.validation.constraints.NotBlank
 import jakarta.validation.constraints.NotNull
 
@@ -18,5 +19,8 @@ data class SaveCustomerRequest(
     val deleteSubsidiaryIds: List<Long>,
     val addSubsidiaryIds: List<Long>,
 
+    val deleteContactIds: List<Long>,
+    val addContacts: List<CustomerContact>,
+
     val id: Long?,
 )
\ No newline at end of file