First of all, welcome to the Forum!
I'm really sorry you had such a bad experience! Did the seller offer any "return" policy in place? If he/she sells other items - look it up! But otherwise you can't do much. Well... Actually, you can give bad feedback. And also you can inform seller that you plan on reporting him/her on ripoff reports (if you have something like that down there, I know there is a site in US) and I believe you can also open a thread on eBay (in Users Discussions or something like that) about it. If the seller sells a lot over eBay, it's possible that he/she won't want to have all this fuss going on over her name. If the user doesn't care - go ahead and report, at least you'll warn other people!
All I can suggest - go with the real stores, which offer the returns. While I know people have great success with eBay I was burned off couple times there (and never used it since then).