Byju's — Cancellation of subscription

My son name is nallabothula Yugendhar
He have taken subscription with Byju's and product delivered. Whenever we felt like it's not working, and we informed to Byju's for cancellation We did number of follow-up calls but no response till and it's not resolved yet, and mentor Manish he is talking rude and while talking they will talk nicely and comes to cancellation talking rude and telling what ever you want do like that talking please do needful... I need help... Please do needful