[Closed] Just about had it with Ebay

Its just people just messing me about then end up costing me money. Sold an item all went smooth then get a message off buyer saying he has bought the wrong part, I had described it perfectly with good photos, Now he wants a full refund including P&P, Don't mind the refund but don't see why I should give him the P&P back after it was his mistake in ordering the wrong part. Would you give it back?