Pick up driver arrived today to take car back in (yes, he had seen errors on screen but didn't know what they meant!!!).
We talked through the faults so that he would know what to tell the service dept and then he went to drive off. Car won't start. Dead battery. Turns over pathetically but not enough to start!!!
Good news is that this fixed the other faults.
So I appear to have a car that drives but has electrical problems or has working electrics but won't start.

An interesting combination.