My son has the above mention C4 and it is driving me nuts.
The car can be locked on the fob and all doors appear to be locked. However when you try the drivers door it opens and unlocks all other doors and the boot.
The same thing happens when you lock it with the key from the passenger door ( no barrel on the drivers door as standard?).
Today he replaced the drivers door lock mechanism and still no joy same issue from outside the car.
He sat in the car with ignition off pressed the fob and all doors locked but the drivers door would not open from inside but would open from outside.
I have yet to get the multi meter out but he assures me he can feel the solanoid being activated and the latch does operate manually ie with a screwdriver if that makes sense.
Auto lock does work when you start driving, however not tried yet to see if drivers door will open when stopped from outside.
Have tried pressing the auto lock before moving, everything sounds normal, all doors are locked except the drivers door, it just opens as if not locked
Over to you experts, sledge hammer being dusted off
) 
) brings back lots of memories.