Byjus Home Tution - Refund not processed after cancellation

I subscribed for Byju's Home Tution for my son Abhijnan Routh (student) on February *, **** by paying the entire amount of tuition fees for one year. The terms were for four weekly classes. Byju's could not find a suitable teacher for the same and changed three teachers for five classes between February ** to February **, ****. I asked for cancellation on March *, **** and since then the counsellor and the Business Development Manager stopped taking my calls. Since then I have made at least ** calls, one complaint in their website, and later emails to their cancellation and customer support teams for cancellation and refund of amounts mentioning my bank account details. Till now, I get a call every alternate day from Byju's saying that the cancellation team will call me up in ** hours and help me with the process. The same conversation and same assurance get repeated while the refund has not taken place yet.