Byjus app TAB - Product not working

I have purchased ur product (*th till **th grade)*.* years back when my son was in his *th grade .He started using ur tab for hardly **days that too because initial mentor support after tat he stopped using because there was no mentor support after that .Then the tab was not working properly and after several times informing ur team and sales person who attend refused to respond. Several complaint i have raised to different person who approached me for the feedback have sent several mail n call but no response or they will say ur issue is registered and will be rectified soon. In the month of Jan an sales person called me n told that they are sending the tab but the sim no need ,he can attend the online classes. But as usual no response from ur side .Ur company is a fraud n cheating like this to people n using their hard earned money.Pls return back my money watever i have paid in full.