How to remove "Request [category_id //from virtuemart]" rule from Joomla module?

Question

PHP

Actually the problem: There is a store on Joomla. There is a feedback form with notification by mail and SMS (about the delivery of the question to the administration). Only in the module code there is a condition where the category_id from virtuemart is taken, so the form is displayed on the main page, but does not work.
====code snippet====
if (($_REQUEST['inquiry_ex']['action']=='send')&& (
$_REQUEST['category_id']!=$_SESSION['sms_lock'] / / will be fixed
))
{
$_SESSION['sms_lock'] = $_REQUEST['category_id'];
if ($_REQUEST['inquiry_ex']['phone']) {
$sms_to = substr($_REQUEST['inquiry_ex']['phone'],1);
$sms_mess = "Your request has been accepted. Please wait for a response."
Tell me how to make the code work on any page of the site. Well, or how to set category_id to it manually?
// the script is not mine. wrote some encoder before me.