Electric problems with VX Commodore

I have a VX Commodore that I am having some very annoying issues with..... What is happening is, when I turn the ignition off, the whole car is dying, as in all power is cutting out - odometer computer screen goes blank and the stereo dies. It is a very intermident problem, but has got worse as now, when i turn ignition back on there is no power in the car..... it has totally died.! The most bizarre thing is, it seems to trip itself back into life (sometimes straight away, other times it needs to sit) and will start normally.... but ALL the settings in the stereo have been wiped and radio station settings wiped..... Holden have put in a new BCM in an attempt to fix it, plus there is a new battery in there, but the problem seems to keep reappearing. Has anyone heard or experianced this before.???