Byju's — Cancellation fraud

I have asked for 15day trail.during the trail period i asked 4gb ram with 128gb rom samsung tablet but they have provided 2gm ram with 32gb rom. So i request cancelling before 15 days. They have not cancelled during 15 days trail period extending the days they asked for plan change from rs. 72000 to rs. 54000. Still now they haven't provided the replacement of tablet. So i requested for cancellation but they said you can't cancel you to continue but my emi is not started. Kindly do the needfull