norfolksybil:...you are not alone...
I'm sorry that you are having to face up to winter with your "EDF" problems but at least you will have your woodburner.
It's a pity that this thread's OP hasn't come back because posts are an opportunity for others to learn. A two way street.
Indeed you are "not alone". There is a common thread to posts about this type of problem. There is mention of DD's set when switched, subsequently increased DDs, alarming account deficits appearing from "nowhere", often suspicion of meter inaccuracy, but usually never any mention of meter readings, though unchallenged meter readings are legally "proof positive" of consumption.
Meter error is not "impossible" but is extremely unlikely. The last thing which should be looked for. There are other more likely reasons such as account registration error, billing error, or inaccurate estimates. Using too much electricity cannot be excluded either, but the key to any investigation is the meter reading.
Get a handle on your consumption by taking daily readings for a week, then weekly readings for a month. Always check that the readings on any bills, whether estimated or actual, are about right. Check that your meter serial number agrees with the meter serial number stated on the bill.
My advice may seem harsh but I mean to be helpful, if not to the poster then to others who recognise the circumstances.