This is a very interesting situation actually!
eBay will usually shoot first and well, not even try to ask questions later. In this case, looks like these guys have filed a report, eBay have simply acted on that report (as they usually do), but from what you write, I would think that you would have a very good chance of actually getting this one over turned.
The first thing you need to do is establish good open communication with eBay, by phone if at all possible. Emails will drag on and drag on, but once you have someone's ear, it's surprising just how quickly things can be resolved.
The bad news, getting someone's ear is the hard part lol.
I would be chasing this up hard with them, I thing you've just been caught up in a big sweep that thee guys have done and no one at eBay has even taken a close look at your situation yet.