I'll bet they were "vidiots"
I don't sell pins on eBay, but over the last 3 months, I've been selling Video cabinets - some reconditioned and some empty cabinets. Initially, I had great dealings but recently, I've had nothing but troublemakers and idiots. Like Greg mentions - place them in your banned eBayer list.
If possible - Cancel the transaction, then relist. EBAy ALWAYS side on the buyer. Their rules are written to protect them. I learnt the hard way - don't bother with "disputes", just ban and relist - and mention that you had issues with the buyer not meeting his end of the bargain. I've been helpful with buyers, only to see them pull out of sales for the dumbest of reasons.