Paytm Mall — I'm complaining about return or refund of my order

Website:

paytm.com

Sir, i had ordered a pair of shoes from paytm mall. Due to size mistake, i had requested to returning that. My request is accepted and courier boy picked up my order. And after pickup, my request was cancelled by the seller. But my order is already sent by me. And i have the pickup receipt. I have complaint about it in their. Official site but i didn't get any solution..
And they didn't give me any reply..

It's all my problem, plz look into the matter and do needful.