Astra G 1.8 SRi Alarm Problem URGENT!

[aruck]

Help!!
The alarm on my 2001 Astra keeps going of randomly.
It did it a few times last summer and then nothing until this week. I'm assuming for some reason it is heat/sun related?!
I turned off the internal movement sensors last night using the 2 internal light switches as the car manual but the alarm has gone off 5 times today.
Do I need to turn of the sensors every time or are they off permanent now until I hold the switches in again?
What else could it be?
Can I turn alarm off?

Thanks

[alphadog]

Had a problem with my previous car (1998 Astra G), where the alarm siren went off, but the horn didn't sound. Made no difference if the car was running or not. Caused by the rechargeable battery in the alarm sounder unit giving up the ghost after 7 years. To remedy, remove the wheel arch liner to the rear of the front passenger side wheel arch and unplug and remove said alarm sounder.

You could get a replacement, but the alarm will still sound the car horn if someone breaks in if you remove the alarm sounder which is there just in case a thief disconnects the car battery.

Hope that helps...