It isn't a question of eBay being "overzealous" in removing your listings. Under eBay's VeRO scheme (see foot of page) eBay has undertaken to remove any listing which the registered brand rights owner reports as infringing their intellectual property rights. Your argument is with the brand owner.
It's possible that the reason for removal isn't actually the copyright of the item itself. Brand owners with exclusive distribution rights may also be able to report items being offered for sale by sellers who are not authorised distributors. eBay tends to lump all reports together as "counterfeit" or similar.
If you search the list of VeRO registrations you should be able to find the registration details for the rights owner concerned, and see exactly what rights they have registered for protection.