What makes you think the "central locking module" is draining your battery? And exactly what is the central locking module you are talking about? I ask because the SKREEM
(Sentry Key Remote Electronic Entry Module), or the CLP/SSM ( Central Locking Pump/Security System Module) are both "central" to the system along with several others.

The most likely culprit as to draining the cars battery would be the VTA (Vehicle Theft Alarm) commonly referred to as the siren. The SKREEM is located behind the instrument cluster, The CLP/SSM is located in the right rear of the car and the VTA, which probably is the cause of your cars battery draining is located below the black plastic cowl at the bottom of the windshield and is accessed by first removing the windshield wipers and then opening the hood and removing the cowl.

AND I really hope you take the advice giving in the #6 post above.

If you have any DTC Diagnostic Trouble Codes to share with us it would be most helpful. We need the numbers like P0410 to really help you with this. Most repair shops will say something like its the "central locking module" giving you trouble, but that really doesn't help in actually fixing the problem. So if you can get a DTC, please share that with us.