I have good relationships with the Service Advisors at my local/selling dealer. However, I don't buy into this notion that we have to kiss up to them to get good service.
First step when a service visit is unsatisfactory is to bump it up to the Service Manager. Normally, that will get it taken care of. If not, take it to the owner/owners of the dealership (General Mgr usually a waste of time; CYA the first arrow in his/her quiver). From there right up the chain to the Regional GM manager, etc.
August 2018 I had my Roadtrek (on a 3500 Chevy Express platform) in for service prior to a Minnesota trip to see my elderly aunts. Around 100 miles into the trip near Mt. Airy, NC, there was a severe knocking from what sounded, we thought, the rear of the vehicle. Local GM dealers didn't have a lift for an 8,000 lb vehicle, so we limped back home on secondary roads. Next day, I took the Roadtrek back to the dealer.
Turns out the problem was a sway bar bushing. When I asked the Service Manager, "Shouldn't that have been caught in the '23-point inspection?", he knocked $200 off the bill. There is a comment on my vehicle profiles now that the Shop Foreman will ensure the 23-point inspection isn't pencil whipped (in so many words) and that all work is properly done.
Paraphrasing Woodrow Call in Lonesome Dove - I won't tolerate poor service.