VECTA Imobiliser on V8s

[smh]

The VECTA Imobiliser (fitted from new) on my 92 v8s is becoming reluctant to let me start the car. It appears to be more of a problem after the car has not ben used for a while. Leaving the key in and ignition on for an hour or so has in the past brought it back to life, but today it seems to have given up completely. I wonder if there is a battery in the VECTA unit that is only charged with the ignition on. The only other symptom recently is that the car has twice, mysteriousaly stopped for no reason but then restarted ok. I can't seem to locate the VECTA company for advice. Removing the unit looks failrly simple except it appears to be tangled up with the alarm that is also fitted. Any ideas ?