Thanks for the input. I'll chalk it up to inexperience and I should have stayed with the guy when he took the RV to check it out when we returned it. I also have no idea if we used as much propane as they said needed to be replaced. They added the treatment to the septic tank before we left and what the guy showed us came out after we returned was like sandy colored oatmeal. I would have re-filled and emptied the black tank again if he had said to, and there was nothing about that in the 10 pages of directions I had to read, either. There was no one rushing me at the place we dumped the tanks before we left the campground. We even used marine grade toilet paper to it would break down better. Guess I just got took by the oldest trick in the RV rental business.
If you were hooked up to electricity you probably didn't make a dent in the propane.
You would have only used it for the stove.
One 20# tank last me more than a month of 3 day weekends using the stove and the fridge.
It goes faster when the heat is on.
The stuff I use in my black water is blue and what comes out is dirty blue liquid. I only flush the tanks out when it gets put away for the winter and again in the spring to flush the anit freeze out.
Even if he charged you for propane it shouldn't have been any more than $20.
I would go to their website and write a review. Tell your story.
It's not right to take advantage of people like that.
I wrote a bad review about Comcast and within 10 minutes they were on the phone helping me out.
"It's not about the fish, it's about fishing for the fish. The fish is gravy."