I probably pay a little more, but I've had all of my service work done on my present coach at a local Freightliner dealer. They have two mechanics that were trained at the Gaffney Freightliner Custom Coach facility and I know the person working on my coach has the training for it. I have a Mercedes (Detroit) engine and having the same owner, they do full service work on both my engine and chassis. I just paid $380 for full service on both the engine and generator including all the filters on both. There was also an extra gallon of antifreeze on the bill and a little labor for checking out another issue.
On my four previous motorhomes, I always used a local diesel garage, but on my present one I decided to use Freightliner, because they would do any warranty work required with never a hassle because they are the only ones that have serviced my coach and have all of my records on file. The owners are great people and have helped me out a couple of times on warranty issues. If I'm paying a little more, it is worth it to me.
On edit, I failed to mention that I get all the fuel filters changed at the same time.