Fleabay has its pro's and cons. I use it frequently out here in the scrub as it gives me great access to items previously unobtainable.
HOWEVER it is a minefield, for both buyers AND sellers. It only takes one with a bee in their bonnet totally unrelated to the transaction who can start real problems. I have twice given a neg feedback, but only after pursuing EVERY option for a satisfactory outcome for each party. Nowadays, I don't bother giving neg feed, I don't need the aggro. I have a list of preferred sellers who I deal with frequently and are reliable to a tee. Caveat Emptor, and I feel for you Rom on the seller's side having to put up with your situation. If you persist with Fleabay's resolution system and stand your digs, they will eventually see reason and change the Fback, if only for the satisfaction of not letting that bugger have a win!