Paytm Mobile Solutions — product has been picked up by the courier partner but they are not refunding my money

I have ordered ironing board costing 4050 rs and I got 1030 A’s cashback.but I found the quality was not up to the mark so placed a return request after Two days ie on 13th dec 2018 .after many complaints the courier partner was ready to pick the product on 25 dec 2018 @ 1.05 pm but updated the status as my return request rejected.now the scene is my product is already picked up but they are denying abt recival of product and not refunding the money back..kindly help