SSG,
I agree with the majority of the posts on this thread and thought I would add my own 2 cents, so take this for what it's worth.
The manufacturer's rep is usually measured in several ways by corporate. One is growing new sales for his territory, another is add-on or implement sales to existing accounts/customers, and usually a 3rd one is customer satisfaction. Each of these measures is dependent on Dealer performance. You could say that the sum of the Dealer performance in each 3 equates to the measure of the rep. What I'm getting at, is the "rep" has a vested interest in you; your spending; and satisfaction. Usually there are corporate goals set by corporate that the rep is tied to. Your treatment by the un-cooperative dealer is not conducive to the rep achieving his goals. (Known as "what's in it for me")
Usually there is an account review of each dealership held between corporate and the rep. Have you heard, as I have, of some LS dealers and other manufacturer dealers losing their license. Your situation is (IMHO) a classic example of why a dealer would fall out of favor.
You should do (IMHO) as others have suggested and appeal to the rep. first, and make him aware of your concerns in the work being done by a convenient dealer and done properly, and in a timely manner. My friend, you have leverage. The rep's job is also to monitor the performance of the dealers and to accommodate customers who for what ever reason are having service issues.
Document your communications, ie., e-mail, phone calls, etc. and go thru the rep first. If you go to corporate first, he may feel circumvented and that won't help your case. I'm confident he can help you in this matter to your satisfaction.
Good Luck
John