Byju's — Sd Card fault..I need refund

I have bought the Course o[censored]psc Ias in march from Byjus ..i only received the sd card..i inserted the sd card on my previous tab but the sd card was not working..it showed that the sd card was not working..then again i reached the customer they told you will replace anither one..nect one came it was alsn not working.
I have paid initial amount 5000 and an emi for 4000 total 9000 i have paid but still now the third sd card came ut was also not working..i have no interest tp go ahead with i need cancellation and immediste refund of money
.I have already sent many emails regarding the cancellation, screenshots etc..i need the cancellation soon
.im not at all interested to continue the course again..