Headphone Zone - Heaphone Zone scammed and damaged my headphones

Hi ,
i listed my * month old Sennheiser hd *** headphones at Headphone zone trade up programme. It trade up programme is a pre owned listing where you can sell you used headphones and they charge ** percent fee for their service. i listed my * month old sennheiser hd *** headphone at *****rs which i bought for *****rs on amazon. the headphone was in pristine condition and fully working with all the accessories and bill.
One buyer placed an order for the headphones. The headphone zone arranged a pic up from my house. They send it to the buyer without even checking it first. The buyer then after * days didnt like the heaphones and intentionally damaged the headphones in order to ask for a refund. the heaphone zone now want to ship the item back to me because buyer asked for refund.

As per their policy i am suppose to get *****rs as bank balance.

It was in pristine condition and fully working. they didint check the product before sending it to buyer. The buyer ,damaged it and want to ship the product back to me..
i lost my new headphone and no money was credited to me as per their policy. please help