Return Troubles

[shanseave-0]

I recently sold an item BN and Sealed the buyer got it said it didn't work and wanted return (I have accepts no Returns) on my listings. He sent it back to me and the part numbers did not match (he gave me an old broken "same item" back in "my" box and the numbers don't match, and somehow eBay took $out of my bank account and gave him a full refund how is this right