If you have not solved the problem go to your local library, they have a Home Energy Tool Kit that you can borrow. You can use it to check how many KWH appliances use and compare this to your account. I used it overnight on appliances like, fridge, freezer etc. from the reading you can work out how much they cost to run for 24 hours. Then I tested the small appliances like TV, Kettle, Washing Machine, Dryer, Dish Washer etc. Had similar problem, double usage, had meter tested, supposedly tested ...