I think the first step would be to tell the manufacturer about this posting to give them a chance to do the repair... at least show a good outcome to this thread. On second thought, it probly best to not let them do anything to it if this is the type work they do.
I would have sprayed soap water to the front screws and gently pushed the bubble down to see where the air is getting thru/ coming out.
I'm annoyed by American companies that think profit comes from getting away from solid workmanship. It's un-American in my opinion. Sorry about the slight rant, but I feel for you having completely exasperating experience with my NL camper.