Info from EK. If you're still seeing this problem contact them for a fix, but it shouldn't be happening widely.
All in all a good response, quite quickly.
"The metering company who own and manages your meter, Metrix have advised that there is a time shift issue with the type of meter which they have installed at your property. They don’t have the ability to send us corrected data so to rectify this issue for you we have shifted your data to bring your data inline and our system will now automatically apply the correction for Metrix going forward.
We have made this adjustment for other people's accounts with your meter type as we receive a report but for some reason your meter didn't come up on it. Metrix are also investigating so that this process is even more watertight. I have run a quick query and can see that our records show that there is 0.76% of these meter types."