Looks to me like this is an ebay shop purchase and not an auction one. I suspect that they are in the right to do this. It's a bit like going into a real shop, seeing something wrongly priced, being told so by the Assistant and offered the chance to have it at the proper price or not at all. eBay has some odd functions in its software sometimes and items listed can't always be changed, so they may have not done this deliberately but are correcting a mistake.

Unless it is REALLY unique, I'd be inclined to leave it and try to find another.

Good luck, Graham.