Byjus learning app - Cancellation and Refund

I have purchased this byjus learning app prog for my son for class **th. During the purchase it was told to me that if I didn't find the product as per my expectations they will cancel it and Refund my money.
First the product was delivered to me after * month of purchase after that it was not working properly so they took another ** days for the resolution.
After that I told them to cancel my subscription as it could not find it as per my expectations.
But every time I called them they always used to give extension for ** days saying that they are upgrading themselves. Now they are not cancelling it. I used to get call from there different sale agents everytime and always assure me that they will do the refund soon. But after that again there is no response from them.
It's a totally fraud company and the people appointed by byjus are totally fraud as they used to trap the customers first and after selling their product they are never reachable