I would suggest perhaps trying to get some proper legal advice in this case, there may be specific procedural avenues you can take, but I'd personally want to make as sure as possible that my appeals couldn't be shut down on any technicalities. (I'm thinking stat decs, any witness statements etc, photographic evidence, or even complaints to the Financial Ombudsman Service, may need to be handled in a certain way). 

I know it won't help much, if at all, but I'm sorry this has happened - I get so angry when I see things like this and eBay needs to take some responsibility for their poor handling of cases like this. 

Ebay should retire the so-called 'Seller Protection'. It's a load of hogwash.

In my 14 years of selling I've never once benefitted from it. However I've been on the receiving end of a lot of buyer protection cases.