No power to Passenger side rear door

My buddies shop has a VW in it right now for a similar problem, affecting two doors with no power plus air bag light going off. His sources say it is the door harness, VW made them too short and wires are stretched at the connector. A new harness from the dealer runs close to $200 per door. You have to remove the door panel and the rubber boot covering the harness. You could possibly replace individual wires in the harness after checking them for continuity, I don't know how easy that would be with only partial access to the full harness. You would also likely need the pinouts or wiring diagram for your model. The wires aren't shorting so you won't get a blown fuse, but they are opening (losing continuity). I know you're not the original owner, but do you have an extended warranty on the car from VW? It might be worth looking into, this is almost certainly a manufacturing defect.

http://gotaclassaction.com/volkswagen-sued-over-defectively-short-design-of-the-wiring-harness-in-2005-2006-jetta-vehicles/ - I know this is for the Jetta, but there are a lot of complaints across the board about lack of power to doors/windows on a number of their models.