Sigma car alarm problem?

[Headless Chicken!!]

Hi, I have a Seat Ibiza which has a Sigma alarm. When I bought the car there was no alarm manual with it. Was working fine until yesterday then just stopped working inasmuch as I am unable to disarm it. Desperately need to be able to shut it up as neighbours ready to lynch me by now. Have been advised that just disconnecting from battery is not an ideal cure. Any help would be very much appreciated.

Donna.
Thank you for the answers so far. The reasoning behind the non disconnection of the battery was I was told it would interfere with the central locking and indicators as they form part of the alarm system. Not sure on this as not much of a mechanic!

 

[J G]

I would have thought that disconnecting the battery is the obvious short term 'cure', at least until you can either get hold of an auto electrician or find a set of instructions or wiring diagram.