RV shops are the same as most motorcycle shops. They over promise and under deliver. One time I dropped of my motorcycle in February. The work was supposed to take 2 weeks. After first threatening legal action and then just threatening physical violence I got my bike back in September.
Different shop, different time, I sent a bike in to be painted. They said two weeks, maybe three. 10 weeks later it was done. I have a dozen stories just like this.
Here is my thing on this. If you cant work on something for a few weeks or months, then don't take it in. Let the owner use it right up to the point you are ready to work on it. They don't do this so they can "lock" in the work and you don't go anywhere else. In my case I could have continued to set up my new motorhome and then brought it to the shop next week.