As i've posted before we have been having troubles with the engine overheating since the first trip we took in the motorhome. Took it to Freightliner twice under warranty and nothing found. Took it ...
I doubt you'll get a warranty claim on a 2008, but you never know. They may give you some assistance since one of their shops missed the issue that should have been obvious. I would express your displeasure and the money you spent and see what they do.
The good news......you know your cooling system is in tip top shape and good for many years.