Well, you need to understand why it isn't working. There is a crank in the
trunk* that will let you open the roof manually. If this works, then the
trouble is electrical, and this can be a faulty switch, blown fuse, or
something wrong with the motor. If the hand crank will not open the roof, or
it will open the roof one way (sliding) but not the other (tilting feature)
then the problem is in the plastic parts that live along the roof rails.
There is a kit of new plastic parts that costs about $50 (USD), and the
installation is a job that some of us can manage at home. No matter what, I
really suspect you do not need an entire new roof cartridge for $2000.

(*) I am assuming that your car has a tool kit that is mounted to the trunk
lid, this kit contains an allen wrench that is shaped like a crank, it's
purpose is to open the roof. The switch that operates the roof is mounted in
a cover that is simply clipped in place. Gently remove the cover to expose
the roof motor.

HINT
If you have a garage door opener that you keep clipped to the visor, you may
find that it will clip to this cover instead. I prefer my door opener
clipped to the access cover to the roof motor because I can't stand anything
hanging from the visor.