RE: Another new error message.
Are you all paid up on your battery rentals? Or more importantly, do RCI know that you are paid up?
Sounds like it could be a message from the connected services people, who have the power to remotely prevent you charging.
Is it a dash board error, or a message that comes up on the sat nav? If it is the latter, then it's definitely something the dealer will struggle with, on the spot.
Either way, I'd make some phone calls first before wasting time going to the dealer.