<?php

function my_em_booking_validate( $result, $EM_Booking ){

	if( empty($_REQUEST['x_card_code']) || !preg_match('/^[0-9]{3,4}$/', $_REQUEST['x_card_code']) ){
		$EM_Booking->add_error( esc_html__('A valid CVV number is required.', 'emp-authorizenet') );
		$result = false;
	}
	
	
	return $result;
}
add_filter( 'em_booking_validate', 'my_em_booking_validate', 100, 2 );