My rear passenger door has been randomnly doing this, however now it is completely jammed shut and won't open at all. The inner door handle won't open it either as presumably it is deadlocked shut. From a search I notice a few people have had this but there doesn't seem to be any real solution. I reckon I can get the door card off, but I think the lock mechanism is behind the inner door trim. Any ideas?
I'm just glad this didn't happen when I had my MOT a couple of weeks ago as presumably all the doors need to work for it to pass.