Paytm Mobile Solutions — promo code not applied and i am being cheated after purchasing a vehicle

Address:

486886

I purchased honda activa 125 and applied promo code worth 7k but now paytm is cheating and saying we cannot apply promo code. I paid a fees of 500 rs and they are now saying we can offer 500rs worth cashback, i am not fool to spend 500rs to get back 500rs. Paytm is cheating customers and they dont have a proper email id to address customer grievance.