Fixing the door
It's not a big job and certainly not worth taking to a garage.
The opening mechanism has a metal rod with some plastic clips attached to it (its been a while since I did mine...so bear with me). Basically, the door doesn't open when the plastic clip come away from the metal rod.
Remove the internal door handle and door cover with a screwdriver so you have access to the opening mechanism. Once you've done that the problem will be fairly obvious. Just clip it into place and perhaps hold together with some plastic wire ties.
Hope this helps.