Central locking Sharan 04 plate

[Pieman]

The central locking on my Sharan 04 plate has stopped working.  The drivers door is stuck in the locked position while all other doors will not lock with the fob. Meanwhile the mechanism sounds like its whirring and the hazard lights flash continually. I am having to disconnect the battery so it doesn't drain, and also so that the car is disabled considering I cannot lock it securely. 

Any ideas as to the root if this problem please?