Its a bit of a tough one. If what you say is correct it sounds like the seller is playing the system a bit, but not actually doing anything wrong ( if all 35,000 listings are for slight variations of the same product, which beggers belief. )  If the listings are for identical products you could report the seller & listings as they would then breach ebays duplicate listing policies. Can you place your product in a similar but slightly different catagory ? I use several very different catagories for the same products and find it makes very little difference to sales which catagory they are in.