diff --git a/constants.py b/constants.py
index f8b0e2f..8f6f5be 100644
--- a/constants.py
+++ b/constants.py
@@ -80,7 +80,7 @@
 PAYMENT_ID = "Payment Id"
 PAYMENT_STATUS_TRANSACTION = "Payment Status"
 PRICE_IN_DOLLAR = "Price in $"
-TEST_TO_BE_TAKEN_AT = "Test To Be Taken At"
+SERVICE_LOCATION = "Service Location"
 SERVICE_CENTRE_LOCATION = "Service Centre Location"
 TEST_NAME = "Test Name"
 TRANSACTION_DATE = "Transaction Date"
diff --git a/controller/master_controller.py b/controller/master_controller.py
index 7dcee32..d2207da 100644
--- a/controller/master_controller.py
+++ b/controller/master_controller.py
@@ -48,7 +48,7 @@ def create_master_entries(table_name: str, data: CreateMasterModel):
             code_values = MasterClient.get_by_code(MasterClient.table[table_name], data.code)
             code_entry = code_values.get("entry", [])
             if code_entry:
-                raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=f"Code already exists for {table_name}.")
+                raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=f"Code already exists, Please use a unique code")
         try:
             MasterClient.validate_master_data(data)
             master_data = MasterClient.fetch_data(table_name, data)
@@ -313,6 +313,11 @@ def fetch_data(table_name: str, coding: MasterModel):
     def update_master_data(table_name: str, resource_id: str, data: CreateMasterModel):
         if table_name not in MasterClient.table:
             raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail=f"Kindly, verify the name.")
+        if data.code:
+            code_values = MasterClient.get_by_code(MasterClient.table[table_name], data.code)
+            code_entry = code_values.get("entry", [])
+            if not code_entry:
+                raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=f"Code does not exist, Please use a valid code")
         try:
             MasterClient.validate_master_data(data)
             if data:
diff --git a/controller/transaction_controller.py b/controller/transaction_controller.py
index ba3bb32..3017120 100644
--- a/controller/transaction_controller.py
+++ b/controller/transaction_controller.py
@@ -17,7 +17,7 @@
     PAYMENT_ID,
     PAYMENT_STATUS_TRANSACTION,
     PRICE_IN_DOLLAR,
-    TEST_TO_BE_TAKEN_AT,
+    SERVICE_LOCATION,
     SERVICE_CENTRE_LOCATION,
     TEST_NAME,
     TRANSACTION_DATE,
@@ -302,7 +302,7 @@ def generate_and_return_csv(service_category: str, start_date: str, end_date: st
             raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="provide a valid query to download the file")
         data = json_data['data']
         df = pd.DataFrame(data)
-        df.columns = [PATIENT_ID, APPOINTMENT_ID, PATIENT_NAME, PAYMENT_ID, PAYMENT_STATUS_TRANSACTION, PRICE_IN_DOLLAR, TEST_TO_BE_TAKEN_AT, 
+        df.columns = [PATIENT_ID, APPOINTMENT_ID, PATIENT_NAME, PAYMENT_ID, PAYMENT_STATUS_TRANSACTION, PRICE_IN_DOLLAR, SERVICE_LOCATION, 
                       SERVICE_CENTRE_LOCATION, TEST_NAME, TRANSACTION_DATE, TRANSACTION_DATE_TIME, APPOINTMENT_DATE]
         timestamp = datetime.now().strftime('%Y%m%d_%H%M%S')
         filename = f"{CSV_FILE_NAME}_{timestamp}.csv"