...oh yes, it's the old "my son bid using my account without permission" line. He did at least message me soon after the auction ended. But it was an expensive item - sold for over £1,000 and I'm furious over waste of time/dashed expectations etc etc. what's more it looks to me as if some kind if snipe tool was used as the bid came zinging in at last second. Seems a lot of effort to me for something you weren't meant to be buying. 
He wants to cancel the transaction - and i sent a pretty snotty email back with reluctant agreement but now think it's risky as if he reneges, I still get charged final valuation fees; is that right? I didn't do a formal cancellation request at least.
The thing is, I'd like to give the under-bidder a Second Chance Offer but if I open an unpaid item dispute I'm guessing I can't until that has all rumbled through.
Oh, what to do, what to do. Would very much welcome a steer...