What sort of "service"? You don't need an RV dealer for chassis stuff, e.g. oil changes, and usually the prices are better and the service competent.
RV dealers love to sell "inspections" or service "packages". They bundle a bunch of things and promise to do good, without having any measurable results. Maybe a checklist with some tick marks supposedly showing things were done. High profit for the shop and easy for the tech to breeze through. Maybe doing a thorough job, or maybe not.
Personally, I never buy such things. However, I've usually isolated any problem before hand and ask for specific repairs or tests, plus an estimate of costs.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL