Byju's — Non refunding amount even after cancellation

I had taken byjus course for my son and he attended couple of classes and was of the view that it is useless and he was not willing to attend last time also I took this course and wasted around 60000 now again I don't want to waste my money so as per their policy I sent intimation to cancel within 15 days period as per their policy, however, even after constant follow ups regarding this, no response kindly help me stop this emi payment simply of no use...