It's tough when a seller pulls this crap. They obviously misled you, and knew they were from the start. Unfortunately, a sure sign of a poor seller is one who does not post immediate feedback after you've made payment. Any delay indicates they are anticipating you may be unhappy, and are waiting for you to post feedback so as to save the old retaliatory negative. (Not all of course that wait to post feedback after payment are pulling this trick, but there is absolutely no reason for any delay of more than 1-2 days!!!)
The best thing to do IMHO is send one more email. Politely tell them that in addition to leaving negative feedback, you will be filing a complaint with Ebay. If you paid by credit card, depending on the bank you may have an avenue to complain through them, possibly to the extent they can reverse the charge.
Like they say, "buyer beware". There are plenty of great sellers on ebay. Unfortunately there are plenty of scumbags too.
At the least, you should post the sellers username here, to warn your fellow videogamers!!!