to seller, just refund the money. maybe you had been cheated by your friend or overlooked on this, it's not your fault. this money can be earned back in the very near future through being a responsible seller. the buyer have provide enough evidence to the case. i had met similar cases before, and sometimes, sh*t happens. learn through it. i'm sure ppl here knows that you have no intention to cheat, but rather have overlooked the situation from the previous owner. just refund the buyer and move on.

bring on some justice!