Hi madkins18,
I'm sorry this happened. I don't have a servicer recommendation, but I have a friend who replaced his damaged door by himself, saving a few hundred $ in labor charges. I don't think it was very difficult.
Btw, I've noticed on some newer rigs that Heartland has started putting a cable on the door to restrict upward movement so it can't get crunched. You might call Heartland Customer Service at 877-262-8032 / 574-262-8030. Have your VIN # ready. Perhaps they'll send you the cable at no charge, and who knows, they might help out on the door.
Another way to avoid future damage is to add
corner guards to the slide out. They'll protect your head and also will keep the cargo door far enough away from the slide out to avoid damage.