Sold some clothing. Buyer contacted saying they were not happy as the item was damaged. I apologised as I hadn't noticed and offered to return for a refund. They opened a PayPal case. They have returned the item via recorded delivery and uploaded the details onto the PayPal case. But the item they've sent back isn't the one I sold! I've messaged them and they claim that's what they received but it isn't! I've never seen this item before in my life, what do I do?