I had an issue with the NCDC 2015 in my Elite, and thanks to TB we now know what the cause of the issue is. I did a search and only found it happen to one other person, but I don't think they ever cured it. But thought I'd post about my experience incase others have the same issue.
2003 Omega 2.6 Elite manual fitted with NCDC 2015 (the one with the telematics in the glove box)
Issue;
The unit would randomly switch itself on no matter if the ignition was on or off, locked or unlocked etc and prompt you to phone the emergency services.
Cause;
The airbag ecu, (located under the centre armrest at the back, in the case of a facelift Elite; under where the heated rear seat buttons are) thought an airbag had been deployed. There was no airbag deployment, but the vehicle thought there had been, this lead it to automatically prompt you to call the emergency services.
Fix;
For the moment the telematics unit has just been unplugged, this has cured it. The battery would be drained if the vehicle was left overnight and until midday the next day.
I'm unsure of what the permanent fix will be, no issue for me at the moment...but TB suggested a multimeter on the ecu, not sure if it's possible to just replace the ecu. But for anyone else with the same issue, a fix to preserve the battery is to simply unplug the telematics unit until something can be done with the airbag ecu.
A big thanks to TB who found all this out for me. And as there aren't many 2015's out there, it's not a massively common issue so could be hard to diagnose otherwise.