I recently sold a sewing machine to a buyer and clearly showed the accessories that went with it and stated no refunds.  I started it at a low price $50 because I wanted to sell it which attracted a lot of bidders.  Even though I just wanted a simple pick up, this one particular bidder was dead set on having it shipped to her so I agreed to cooperate with her sending a courier (as expected it was a pain as I had to wait at home for days for them to turn up) .  So she gets the machine for an absolute bargain and then downloads a manual which tells her that it should have more attachments.  She wants a refund.  I go looking for the attachments and find them (I'd forgotten I had them).  However I realise that the attachments would have gotten my item a much better price had I listed them.  In the meantime she's unpacked the items an tells me how she's spent so much time cleaning it up (it was fine when I sent it).  I don't really want it back now as a) I don't really have the time to deal with waiting around for a courier to deliver it back to me and b) it's not really in the same condition anymore as she's unpacked it and been fiddling with it.  I offer to send her the extra attachments for $60 incl postage.  She says no so I say $50 (still an absolute bargain but it seems nothing is going to make her happy at this stage).   I feel as though I've done everything right and bent over backwards to accommodate her but her last messge was pretty angry and  she is going to lodge a complaint.  Not sure what I've done wrong here?