Sorry to hear you're having those problems with your Isuzu, and with your dealer. My dealer has been great to work with - the only possible knock I can give them is that they are so busy it takes a while to get on the schedule (they work on Hyundai's as well ).

Back to your issue though - that sounds like total BS! You have a warranty & your problem is a warranty issue. The fact that it was repaired before and has the same problem is a non-issue (unless they are saying you caused the problem). The person that last repaired your vehicle was an authorized Isuzu warranty repair facility - it is not your problem that it needs the same repair again! They need to get you going and THEN worry about the back office crap!
I would call the owner of that dealership and tell him he needs to take of your issue immediately. The pass-the-buck deal is not your problem. Obviously that dealership that has gone out of business is not going to repair your car or stand behind its repairs. If they made a mistake - that is something that Isuzu needs to handle - it is NOT your problem.