Not got around to using Toaf Android yet, I'm still using XP.
Try searching the forum for CAN bus faults and you get results like this one
:
https://the75andztclub.co.uk/forum/s...d.php?t=211877
I believe this problem is often related to wet inside the car (yes I know it hasn't rained there for months) but have you had any problems with water in the boot or cabin, has the car got a sunroof?
As the Rover 75 shares much of its electronics with BMW, perhaps a BMW garage could be worth speaking to.
Good luck