You could try again to direct ebay's attention to the proof of authenticity that you originally provided in the listing but I'm not optimistic it will make any difference to the decision ebay has made. In my experience, once ebay has made a decision they rarely reverse it (unless legally forced to !!)

I also sell designer wear and very occasionally assessories and I have learnt over the years which brands to steer clear of as there are so many knock-offs of those labels in the marketplace and people (and apparently ebay as well) are always sure you are trying to sell fakes rather than authentic items. These include Chloe, True Religion and Louis Vuitton.

You may just have to write off this particular item or try selling on another site.