I've never had this problem on a Passat but I've had to fix several Golfs where this has happened. If all the banging, pulling, etc doesn't release the lock then (in my experience) you usually have to split the actuator casing to get the door open. Once you've done that the chances are the door wont close, so I wouldn't do it until you have a new actuator to fit. On the cars I've done, getting the inner door panel off hasn't been much of a problem. There is a Torx T20 right on the bottom of the panel that can be a bit tricky with the door still closed. Splitting the actuator casing usually involves attacking it with a big flat blade screwdriver and a hammer. Just be careful. You don't want the screwdriver to slip and punch it's way through the outer door skin

Regards.

Jim.