Dealership can't find or fix problem, what are my options?

This isn't on my Tacoma, fortunately, but on a Ford Transit Connect that I use for work. We bought it used, and the previous owner purchased the 0 deductible full warranty, so everything is covered. The thing is pretty much a giant piece of shit and has had about 4 grand worth of work done in the last few months, but there is a very bad grinding/thumping noise coming from the rear brakes. I had 3 different mechanics check the brakes and they all told me that everything looks perfect back there. The service writer at the dealership gave me some complete line of bullshit about the drums being warped and the brakes needing a new hardware kit, to the tune of 600 dollars. He guaranteed me that this would fix the issue, even though I knew it wouldn't so I told him to go ahead and do it, but that I would be bring the vehicle back in every time it makes the noise afterwards. Of course, a few days after picking it up, the noise started again despite having all the new parts. It's clear that the dealership can't find the problem, and that they charged us 600 dollars for nothing, but I still need to get it fixed as it is incredibly annoying. FORD corporate has been of absolutely no help and they even tried to deny some of the previous claims despite the warranty.

 

Ford is the worst. My company bought 10 Ford diesels between 2006 and 2008. All of the dealerships around us refused to work on them after 2009 saying that Ford no longer accepted responsibility for them because they were designed by International. We had several trucks that cost $60-70k with less than 50k miles on them sitting in the back of the dealer lots that no longer ran and they refused to touch. The regional Ford rep wouldn't return any calls at all. We ended up dumping them for pennies on the dollar. I will never own another Ford.

 

Lawsuit.

Sell it.

Not much in between except more of the same.