Created a fail case for non-existent customers

src/updateCustomerAccountBalance.c

@@ -18,6 +18,9 @@ void troubleShoot(int errorCode){
         case 3:
             printf("Renaming of a file failed. Are you sure the bank management system has the required authorization to rename files?");
             break;        
+        case 4:
+            printf("Could not find the customer. Please contact customer support.");
+            break;
     }
 }
 
@@ -61,12 +64,13 @@ void replaceBalanceInString(float replacementBalance, int currentLine) {
     char balance_as_string[MAX_LENGTH];
     sprintf(balance_as_string, "%f", replacementBalance); //converts replacement balance to string
     strcat(newBalanceLine, balance_as_string);
-    replaceLineInFile("CustomerData.txt",currentLine,newBalanceLine);
+    replaceLineInFile(CUSTOMER_DATA_FILE,currentLine,newBalanceLine);
 }
 
 bool updateAvailableAccountBalance(int user_id, float newBalance){
 
     bool keep_reading = true;
+    bool foundCustomer = false;
 
     char *buffer = malloc(MAX_LENGTH * sizeof(char));
     char *stringID = malloc(MAX_LENGTH * sizeof(char));
@@ -78,7 +82,7 @@ bool updateAvailableAccountBalance(int user_id, float newBalance){
     sprintf(user_id_as_string, "%d", user_id); // converts user_id to string
     strcat(stringID, user_id_as_string);
 
-    FILE *file = fopen("CustomerData.txt", "r");
+    FILE *file = fopen(CUSTOMER_DATA_FILE, "r");
     //printf(stringID);
     while(keep_reading) {
         fgets(buffer, MAX_LENGTH, file);
@@ -93,10 +97,17 @@ bool updateAvailableAccountBalance(int user_id, float newBalance){
             }
             strcpy(balance_String, buffer);
             keep_reading = false;
+            foundCustomer=true;
         }
 
     }
-    fclose(file);;
+    fclose(file);
+
+    if(foundCustomer){
         replaceBalanceInString(newBalance,currentLine);
+    }else{
+        troubleShoot(4);
+    }
+    
     return true;
 }