Just had a letter through the post from NPower saying we owe them this large amount of money for gas bill?! I live in small 3 bed house with only a new, modern boiler, No gas fires or cookers etc... It doesnt say from which point(s) we have owed this, I only has my statemt last month with our usual monthly payment, and now this, What is going on?

Just rememberd we had our metre changed a good 6-7months ago due to a leak, Could these new readings have made it look like its gone around the clock back to zero, Its reading 4756 at the moment.