Hi Neil, your door latch is worn, to gain access you have to remove the door card and then with the door open you will find two big phillips screws one on the bottom egde of the door and the other above the three screws that hold the latch assembly in with the two screws removed you can remove the anti-theft guard that covers the latch assy(you will have to cut the mastic along the edge) remove the three screws holding the latch into the door and you can remove the latch, if your lucky a good spraying with WD40 might give you a bit more life out of the latch but ulitmately it will need replacing
nigel
February 2008