If anyone has any experience of this or could shed any light on this I would appreciate it greatly.
The central locking mechanism in the drivers door seems to have failed.
The remote control will lock / unlock all doors except drivers door.
The key, when used in the drivers door will lock / unlock all doors.
So basically it means I have to use the key to lock and unlock the car at the moment.
Could this be something very simple or is it a garage job?
The lock has been replaced but the situation is exactly the same!!
Does this mean that the mechanic needn't have replaced the lock at all?
The control unit under the floor on the passenger side has been inspected and is dry, apparently this unit getting wet is a common enough problem...
I had a related problem some years ago when the remote wouldn't work at all.
The advice at the time was to insert the manual key into the drivers door lock - turn the key - and hold it for a few seconds in the turned position. It seemed to work although whether the initial "freeze" was just a once-off or not, I don't know.
For some reason, this was only a problem with one remote key - the other one worked perfectly.
The circut board that controls the locking mechanism is known to fail on the VW golf. The metal soldering spots on the board crack causing the problem. Probably the same part used on your A4. Here's the explaination http://forums.vwvortex.com/showthread.php?1542461
The solution to my problem was to replace the window winder control unit as suggested above by TONNEMAN72.
The mechanic originally replaced the lock but this didn't solve the problem so it went to a specialist auto-electrician and he replaced the window winder control unit.
Hope this helps