How can I fix my ussd from looping in php (Mtn-Comviva) [closed]

I am developing a ussd code with mahindra comviva http pull service interface. I got connected with the server. When anyone send a request by add ussd, recieve response with menu option. But there is no input box to add the option in USSD popup on mobile.

In document it says we need to use ‘freeflow:FC’ to continue but it is not working. A little help would be appreciated. My menus on the other hand keep looping.your text

<?php header('freeflow:FC'); echo $response;

Normal flow in the menus