Alarm keeps going off

Hi all,
I have a passat B6 Estate 140 sport 2006.
All was well until this morning when I went to lock the door with the remote and within 30 seconds the alarm was sounding. I unlocked and locked the doors again and exactly the same. All doors, bonnet and boot were closed properly and all the windows were fully up.
I have had my VCDS on and it came back with 1 fault found:
01134- Alarm Horn (H12)
004 - No signal/communication - intermittent
I cleared the fault and all was well again for a few minuets when the alarm was sounding again. Cleared the fault about another 5 times but the same fault keeps coming back.
Does anyone know how to rectify this problem as I am having to leave the car unlocked!!
Can I dissarm the alarm via VCDS and if so how do I do this?
I am desperate for a solution as I can't keep leaving the car unlocked.
Thank you in antisipation.

The alarm Horn is under the drivers side wheel arch, behind the plastic cover. It can be a pain to get off because it is in a box with security bolts holding it on.
I haven't noticed a VCDS setting to turn the alarm off.

Hi Martin,
Thanks for the info.
I went to the car this morning after leaving it unlocked all night, locked the car with the remote and the alarm set without trigering.
I lowered the window and left it open, locked the car with the remote again and when the alarm had set it self I put my arm through the open window. The indicators started flashing but the horn did not sound. I connected VCDS and now I am unable to clear the fault, it now says that there is no communication with the horn, where as before it said that the signal/communication was intermittent.
Also whilst the car was locked with the remote I tried to open it with the key to see if that triggered the alarm. The door would not open.
This leaves me with another dilemma, will I be able to gain entry to the car if the battery goes flat?

I had a very similar issue with the alarm on an A4 B6. It was the battery in the alarm siren. Battery is not replaceable so had to replace the whole alarm siren unit (H12).

Cheers Xenon,
I wonder if anyone knows if this is the case, would I be right in saying that if I just leave things as they are I will not have a repeat of the alarm not setting its self and the horn sounding?
Does the (H12) horn take any power from the vehicle's 12v power system which would make it sound?
Will I be able to fit a H12 horn from a salvage vehicle or are they coded to the vehicle/imobiliser?

It sounds like the alarm horn is the fault, rather than the alarm system. If horn doesn't sound, it shouldn't drain the battery but it might because of the can-bus system.
If battery goes flat you can still get in with key. A secondhand alarm horn may not be easy to get as it is fitted to the car with security bolts. It isn't coded to the car so a second hand one should work if you can get one.