Problem with trans function

I’m trying to update a form submission on my website. The code I’m using is as follows…

require_once(ABSPATH . 'wp-content/plugins/contact-form-7-to-database-extension/CFDBPermittedFunctions.php');

function calc_balance_due ($var_booking_id) {
require_once(ABSPATH . 'wp-content/plugins/contact-form-7-to-database-extension/CFDBFormIterator.php');
$exp = new CFDBFormIterator ();
$exp->export ('Booking Details', array ('show' => 'BalanceDue', 'filter'=>"booking-id=$var_booking_id"));    //booking-id is a unique key in the Booking Details Table
while ($row = $exp->nextRow()) {
	$var_balance_due = str_replace (',' , '' , $row ['BalanceDue']);
}
$var_paid_amount = $cf7->posted_data ['paid-amount'];
$var_balance_due = number_format ($var_balance_due - $var_paid_amount);
return $var_balance_due;
}

cfdb_register_function ('calc_balance_due');

function before_sent_mail_actions () {
$var_booking_id = get_query_var ('booking_id');
$shortcode_text = "'[cfdb-table form=\"Booking Details\" trans=\"BalanceDue=calc_balance_due ('".$var_booking_id."')\" tfilter=\"booking-id='".$var_booking_id."']'";
do_shortcode ($shortcode_text);
}

add_action ('wpcf7_before_send_mail' , 'before_sent_mail_actions');

I have set the Run any function in shortcode option under the plugin options to true. But for some reason that I can’t figure out to save my life, the BalanceDue field on the Booking Details form just doesn’t get updated.

If I populate a dynamichidden field (using the CF7 Dynamic Text Extension plugin) on a form with the calc_balance_due function, it returns the desired value. And I can get around this problem by doing that. But that would only mean data duplication and redundancy.

Could someone please help me with where I’m going wrong here? Thanks a ton in advance.

S

https://ww.wp.xz.cn/plugins/contact-form-7-to-database-extension/