You can get a normal repair man to fix an RV door. It is not that hard of a job. Especially since RV doors are alot smaller then regular doors. You can also get a car repair man as he will know how to fix it most likely. They're similar jobs.
You can try to go to a local car dealer and ask if they will attempt a repair in their shop, however they may refuse. Your best bet is to go to an independent repair shop who will have the tools and mechanical expertise necessary to fix an this type of unusual repair.
There is a good place in Bellflower, California called Smith Butane Service - they have fixed my family's RV before and are extremely good and reasonable. Also, you can always get a manual and learn how to do it yourself!