Paytm Mall - Wrong product delivered twice

We ordered a puma jacket for Rs.**** from Paytm mall on *th December using a coupon code for which we got a cashback of Rs.****. The product delivered was wrong, instead a track pant was delivered and Paytm gave no option of replacing the product. Instead, we were forced to return it and order the product again.
Now, Paymt is telling that we will take the product but no money will be refunded becasue they gave a cashback of ****rs. We are trying to tell them that because of their negligence we got a wrong product and we lost a coupon code of ****rs for which they are not willing to take any action.
On **th December, we ordered the product again and on **th December, we again got the wrong product i.e. the same track pant. This shows the kind of service Paytm is rendering to its customers.

We called the helpline and all they are saying is return the product so we have * useless track pants to be returned and the product we want is now out of stock.