I think it can be very variable the amount of use and the economy of household items that use these supplies. For example your boiler might be inefficent at heating water, your house might be poorly insulated. Are some items still connected and running on the electicity even though you are out such as fridge/freezer, security systems, video player, washing machine, slow cooker???
Whens the last time your meters were read, they may be estimating more for the christmas period as most people use more over that period?
If this is still high without it being estimated turn everything off and check the meter is not going round, turn items on in the house one at a time and see the meter go round faster, it will give you an idea what items cost to run. Start keeping a table of meter readings say 2 twice a day on the way to work and on the way back write the meter reading down with the time and date each reading was taken and then you might see a pattern, or a problem you can then bring up with your provider.
Maybe your supplier has just increased their prices like Powergen?