I had the same experience with our Class C.
I have always change my own oil. My Ford E450 is the easiest rig I have ever owned to change oil on. One day, I didn't feel like messing with it before a upcoming trip. I asked the J-Lube drones what it would be to change the oil. They quoted me $100. They said just because it is a Motorhome. I asked them what they were going to service on the fridge and the stove? Otherwise, it's just a van. Blank looks and confusion led to pointing at the neat little pricing chart on the wall. I changed it myself that day, and have never taken it anywhere since.
