Well, Tetbury is not far from me, I was quite close earlier today, but not free to stop.
Is the disconnection of the B&M the reason for the flashing milage? Or is there another problem?
If B&M has failed, and you do not wish to get it mended, then a proxi can be used to tell the system to not look for it, and stop the milage flashing. Can be added in again later, if repaired.
If there are, or might be other issues, we can read the system and see what it says.
PM me with availability, we can sort a meet.