I also am pissed with sedo - in their recent "no reserve auction" I "sold" 2 domains, one for $5500, the other for €3250. Neither sale went through to completion with both showing in their bullshit negotiation area as "Buyer failed to pay, transaction cancelled" or some bullshit or other

I did contact them to ask to sell to the next highest bidder but they simply replied that the transactions were aborted, and they are now again on sale at Sedo.
Nearly $10k lost cos of their incompetence
--edit
I do wonder whether they were doing the shill bidding themselves knowing full well there is no recourse....