[swarmee]

You might want to PM Leon to have him move this to the main board to get more responses. I have never heard of them.

Do their terms of service allow the house to bid on items? If so, they might have been shill bid up and then the house bid an extra amount and your friend didn't bite. Or it could be honest and the auction house was told the buyer wouldn't pay. How many days between auction end and failure to pay? Did the auction house say that they banned the bidder? You could ask if they did.

Your friend could also counteroffer that they would only pay 1 increment above the 3rd highest bidder, since the highest bidder wasn't a true competitor.