Posting here purely for traffic, in case this is useful for anybody.
For the last 18-20 months I've been using a smart meter for energy readings. My dd has increased a few times and is roughly double what it was originally. I didn't really look into this because of the energy price rises.
Last month I was request to send manual readings so I did. Then I was asked to send a photo of my meter which I did. This morning I checked my app- I was £2900 in credit. I phoned to check and the smart meter had been sending inaccurate readings so I'm getting a refund.
Don't relay on smart meters!