mate this is the same prob i had 2 weeks ago but didnt no the solution untill i got robbed for £144 by vauxhall, i later learnt it is a commen fault in the sounder that occures when the batteries die, i could have just brought the sounder for £44 or later i was told just replacing the batteries for £12 could have fixed the problem, mine still went of when only clicking the lock button once to, drove my neighbours mad for a weekend munchies..