have a puma 2.2 with an aftermarket alarm

Recently the alarm has stopped disarming the puma immobilizer. A recent visit to a garage they were reluctant to start digging around the aftermarket alarm and recommended carrying the puma fob and the aftermarket fob.

So now I have 2 fobs for the car which is a pain.

Is there a way to disable the puma immobilizer as my aftermarket alarm has it's own immobilizer cutting the power to the car completely instead

Thanks