Hi,
I've found that I have the same problem after being with Scottish Power for nearly 7 years.
I had actually called to find out if I was on the best price plan possible, due to the price increases that are coming in shortly.
After providing up-to-date meter readings, I was asked if I knew which rate was which for my electricity, as I am also on Economy 7. I stated that Rate 1 was the Day Rate, and Rate 2 was the Night Rate, to which I was told that on their system it is actually the other way round! We agreed that they would call back an hour later so that I could confirm via the readings on the meter, which reading what which.
So, to cut a long story short - I'm right and their system is wrong. I've been inputting the figures correctly (Rate 1 for Rate 1), as have the gentlemen who do the yearly meter reading checks. So it's all Scottish Power's fault.
I'm now also being told, that even as a household of 1, I'm using energy that is same for a family of 4, which I find totally unrealistic as I don't have anything more than the standard in my house. I don't have a dishwasher or a tumble dryer for the main reason of their energy consumption, so now I'm completely flabbergasted by the potential of any "arrears" being backdated (I have been assured that this won't happen, which I'll wait and see about due to past dealings with British Gas which I did actually say to the guy) but I'm also stunned at my apparent overuse of electricity that I'm being told about when I don't have anything in my house that could account for it. My appliances where in grade A when I brought them and they're not that old!!!
Is it possible that my electricity meter is wrong? I've been searching online, and have found that it can happen for prepayment meters, but mine isn't one of those.
Can anyone help?