Sometimes if they keep breaking they are attached too tight to the bottom screws. The shade should go up and down real easy with just two fingers. If it's hard to push up and down loosen the line going to the screws. Also pushing them both up or down at the same time breaks the strings.
As far as paying someone to fix them you don't have to do that anymore.
All the camping stores are now carrying a kit with string and screws to do it your self for just a couple bucks.
That all said a shower tension rod fits right up under the side valance on most RV windows. Then you just buy room darkening drapes. I did that in the front windows and do like it better than the day night shades.