Snapdeal.com — Courier service didn't pick the order for Return

Address:	110020
Website:	Their delivered product

I have received an order of a Jeans on 17th Oct'16, but size was not fine so I placed a request for return next day. But no one called me for pickup and on 25th Oct, they have closed the return request.
Now when I am telling them to exchange, they are not ready to do.
Please help me to get exchange this product or return.