Byju's — Cancellation subscription

Order Id number is SO-[protected]
We are not satisfied with byju education system this is only pre recorded videos system and my child is not able to learn from this tablet(videos). byju product(course) to received me at 30 July. Before purchasing byju course. Executive said to me that if you will be not satisfied with in 15 days of receiving course then we will return your money. Now I am trying to call them and costumer care number showing me always unavailable and I sent many mails for cancellation but byju team are trying to force to me for keeping this product.