If it was an auction, perhaps the end price wasn't high enough for the seller so they are refusing to sell so cheap (some sellers to this). Did they relist the item?
I would suggest you leave negative feedback stating the seller said the item was no longer available. The seller is not allowed to sell items they do not have, can't get to the buyer within a reasonable time or have been listed somewhere else.
**********************************************************************************
Non payers should get unpaid item strikes and be added to block bidders lists. Period.