Pontiac Montana 2002 leak

I have a Pontiac Montana 2002, which I had Gm look for leak on at

56,000 kms and tested, it was clean, yet I had to add coolant before the test. Now the van is at 65000 and again I have to add coolan. So, GM Knows about the intake manifold leak. I have proof that the coolant was down and added before the warranty expired and now after expiration. Has anyone had a good experience with GM fixing this problem, at their cost? Jim.