They're supposed to only retract in certain circumstances, such as putting in a wrong figure. The ebay instructions imply you are then meant to enter the correct amount etc

But basically bidders seem to be able to retract pretty much at will, up till the last few hours of an auction.

There's nothing you can do & no, there are no consequences that I know of.

I understand where you're coming from, saying you've potentially lost customers. I know when I watch something which is then sold to someone else or where I am outbid, I pretty much put it out of my mind and move on. A couple of times I have had second chance offers come through and thought.. what on earth can it be for as I have forgotten what i bid on days before, till I open the message.

If you don't want this happening, you could list your items as buy it now or buy it now/ make an offer instead of auction format.