Annoying Alarm on my s4

[Bisonone]

My alarm keeps going off when car is locked. I can hear a noise coming from the drivers side rear quarter panel, just behind the light in the boot. It's a strange sound like an electrical croak, it's a faint sound not loud. I know that sounds funny, but it's the best way to describe it i think

I've tried unlocking and locking the car, turning the ignition on and re-locking the car again after all this the alarm still goes off.

When i unlock the car but dont open any doors and then the car re-locks itself, thats the only time the alarm doesn't go off by itself......

Any help would be appreciated as it is doing my head in now.

Thanks!!!