Byju's — Foundation Course Cancellation and Refund

I was sold the 2 year NEET online course (a tab, books and videos basically) by BYJUs making a promise that if we don't like it, you can cancel at any time. And then they also kind of forced me into getting loan from Fullerton for INR 120, 000. After about a month we realized it is not that great to have online mode and wanted to send my son for offline coaching.
When I requested the cancellation by calling the sales guy who sold me, he asked me to send an email regarding that to his official ID. It's been 2 months now, we did not get any response and he does not answer our calls either. So I was misled into buying the product.
I have stopped paying the EMIs now, only to get threatening calls from Fullerton.