:rolleyes: Hello, My name is Roy and i had the same problem with my mk4 (1997) diesel van, both wouldn't unlock with the key but the locked O.K. I solved the problem by removing the door liner and removing the lock mechanism from within. you will see on the lock mechanism a slot where a nylon slider goes up and down, the nylon slider becomes slightly worn which means you have to get a new lock. To get around this i slightly squeezed the metal slot together making sure that the nylon slider could still go up and down but with a little resistance. I did this to both doors and have had no further trouble for the last six months. I hope this helps. Regards Roy.