There is a link in every listing to report it to eBay. How much notice they will take is another.
If you're saying that you can prove the existence of over 600 fraudulent listings you could try contacting customer support.
There is no buyer protection of any kind for motor vehicles sold on eBay. Regrettably so many buyers never read this that eBay motors is a magnet for criminals. In a TV programme about organised crime, a senior police officer reported that one criminal gang alone had registered "multiple hundreds" of fake accounts on eBay to place fraudulent listings for non-existent motor vehicles.