I have heard other such claims of online purchased pokemon games, and believe from this that it probably isn't wise to buy them.
Also I years ago left Ebay for the more reliable Amazon. I begun receiving tons of emails concerning listings that were not mine nor sounded like items anyone who knows me well would expect me to have, it was several listings when I only had posted one. So I signed on to the account and found my account displaying said listings. I of course emailed Ebay immediately, and they put my account on some special lock down that prevents pretty much all activity except sending and receiving messages. They didn't do much beyond that(so some help they were), and I never figured out how long it was supposed to stay and how to remove it.
I got worried anyhow and never returned. It was a real shame actually, I had a good rating on that account, I had 100% positive purchaser ratings.
So I prefer not to trust Ebay but regarding games you need to be careful anywhere online because it can easily be listed as new and/or legit when it really is not. I wish you luck getting a refund; Amazon helped me well to get a hold of a seller whose item never arrived and I got a refund right away. As I said I believe them to be much more reliable.