I am with Executive, Jallen, that Go(blank)Go Guy (it's almost NFL time and damned if I'll cheer for the cheeseheads!) and several others. We must be missing a whole bunch. First, I don't see how a leaking fuel line could cost $4000, but then again I can't see how you can get $85.00 a day to store an RV, especially from people on these forums, since they balk at any full hookup RV site over $25.00, but that is a different story.
This all supposedly happened in July and now it is late August. Why hasn't the OP plopped their arses in the dealer's office and gotten this hammered out? The dealer has no service department, but has service writers? They can be contacted to buy the rig, to set up delivery, but can't be reached now? Maybe they need to try *67 and block their number from the dealer's caller ID.
If someone started calling the local government, licensing departments and the like, you can be assured I would never do a thing for them. Actions like that only lead to one road, the courtroom. And with a used vehicle, and almost assuredly a signed AS IS NO WARRANTY document, I like the dealer's chances in that courtroom.
In my opinion they should get the rig repaired. I would make a phone call to a couple of diesel shops and cross check that repair estimate for a leaking fuel line. If $4000 is way out of line, I would drive the rig to the other shop. It made it 550 miles, it will make another 10 or 20. If I have the shop it is in make the repairs, I would be looking to get the storage waived. I would take all these receipts to the selling dealer and try to nicely, but firmly reach a settlement agreement, maybe dealer pays 100% or maybe dealer pays 50%, I don't know. I would get the dealer to honor any other of their commitments and I would move on. Only if I got nothing from those efforts would I start thinking about using the legal system.