eBay doesn't give a crap about sellers, and you are up the creek.

Fact is, they bend over backwards to buyers. If someone wanted to dishonestly acquire half a dozen bicycles, they need not steal them off a bike rack; all they have to do is buy them on eBay, claim seller fault after receiving, retract payment, and jump through relatively few hoops to wind up with - essentially - a free bike.

-Kurt