I have a 57 plate Freelander 2. When locking using the key fob, all doors lock except the n/s/r. If I then push the lock button a few more times this door locks. Then when unlocking all doors unlock except the n/s/r. I then have to push the unlock button 3 times for it to unlock. I have been told its the central locking module in this door. Has anyone come across this before and are they difficult to change? Snap 