Thanks everyone for the replies, i will def be calling them tomorrow to see what on earth has happened. I did a check of the meters and they all look right, and DF called last quarter to make sure they had done an actual read as it seemed low for winter and they assured him they had. Hopefully there is some other error on their part, there was an article in our local paper recently warning everyone to check their bills carefully if they had a sudden spike as people had been having issues so hopefully this is related! DF is still being an absolute PIA about it, he even turned the tv off mid-show on me and said we need to be more careful about our electricity consumption...!