Alarm going off when door opened

My Vectra B CD has the factory fitted alarm, how do I stop it going off if I
unlock the door manually (with the key rather than the fob).

Thanks in advance
Mark

 

My Vectra A was like this and my Corsa C. As far as I can recall that is
the way it works. Once you have the door opened you needs to switch the
ignition on to silence it.

Ian

 

Same with my vectra A as well. Only way round I can think of is to lock it
manually with the door button rather than the key or fob.

But why not simply use the fob?

Mike

 

That's the way it works. Any locking method sets the alarm, and it can't
differentiate between using the manual key to unlock and someone using a
probe in the window slot to release the lock. The only way to silence it
is to have a key with a working plip or that fits in the ignition lock