ok but just to clarify, if i use the lever on the passenger door, this does lock the passenger door and all of the other doors so the central locking works this way around, but on using the key or the fob, the passenger door does not lock / unlock. Do you still believe this to be the locking mechanism?
Thank you for your reply. Initially I thought that the lock mechanism may be the issue, but the lock does work if I use the switch on the inside of the door. Would this not indicate that the lock mechanism is in good working order?