Currys PC World refunds are paid from customers? pocket

Bought a Logitech webcam from Currys PC World shopping apr. 5 days ago and came next day. All was fine with shipping. But the optic of camera was like it has damaged inside. It was not showing me as it supposed to show. I asked for a Curry PC World refund. They accepted if I send the item back. So I had to pay extra 4 bucks to send sth which was not my fault even. Sillier than silly!