Been there .... done that .... this all sounds so very familiar. Often it is mostly my own fault when this happens, as I don't look and read carefully enough to discover the sellers mistakes/diseptions, but sometimes it is wholly on the seller. In those cases it pays to be as unforgiving as the system allows.
In this case, the item is clearly misidentified, thus there should be no question that eBay/Paypal will find in your favor ..... but it will take time.
The seller would be smart to cut his losses in this case, and release you from the deal, before the system comes down on him officially.