case 'update_customer_form':
                $customer_id = filter_input(INPUT_GET,'customer');
                $customer = get_customer_details($customer_id);
                include('View/update_customer.php');
            break;
            case 'update_customer':
                $areacode = filter_input(INPUT_POST, 'areacode');
                $phonenumber = filter_input(INPUT_POST, 'phone');
                $balance = filter_input(INPUT_POST,'balance', FILTER_SANITIZE_NUMBER_FLOAT);
                $customercode = filter_input(INPUT_POST,'custno');

                update_customer($customercode,$areacode,$phonenumber,$balance);
                header("Location: ?action=cust_details&customer=".$customercode);

            break;