I've had the same problem. The shops at motorhome dealers need to get more in line with the shops at car dealerships. The car dealers are all about customer service and making sure people come back and buy their next car there. RV dealers don't seem to care so much about that.
Also, I think there is an issue with the repair people who work at RV dealers. You generally have to be a mechanic to work on the engine and driveline, but I don't think there is any similar requirement to have any training or certification to work on the house parts of the motorhome. I think they simply hire people off the street and then they get on the job training in how to fix things on an RV.