Think Learn Private Limited BYJU S - Not satisfied and unable to understand anything

I bought a *th standard course (tablet) for my daughter from Byju's (Think & Learn Private Limited) for Rs. *****. I was informed by the Byju's authority that if I will face any problem (such as satisfaction, understanding problem etc.) from the course, in that case I can cancel the course by sending a cancellation mail within ** days of receipt of the order. Also I was informed that if I cancel the order within ** days then I will be able to get full refund. I received the order on *th September, **** through Blue Dart courier. After * days of use of the tablet my daughter was unable to understand anything from the course. Byju's totally dissatisfied us. So I decided to cancel the course on *th day. I sent a cancellation mail to byju's support team but not responded. I mailed, mail after mail, tweet and call after call but got no response from Byju's end. I was cheated by Byju's. So, I decided to file a complaint against Byju's in voxya.com.