Locking Fuel Cap Blowing Fuses

Hi, I have a 2000 VW Bora. When I press the internal pushbutton inside the car to open the door to the fuel cap, one of three things happens. 1. Nothing. 2. The fuse blows, this also takes out the central locking. 3. Very occasionally, the door opens normally. Anyone any ideas?
If it is the door opening mechanism, how do I change it?
Thanks for any help offered.
Regards
Gary

Comfort control module is faulty.

Thanks Jup,
Where do I find this module? Is it easy to change?
Gary

behind driver side knee pannels and metal knee bar. Its on the left of the steering column above the relays. If you replace it the key fobs will need to be reprogrammed to the vehicle at a dealer.