I went with Npower a big big mistake I paid their bills promptly, then out of the blue I got an energy bill for £1,800 when I enquired they said they had been undercharging me ! boy did I complain and complain after much deliberation they reduced it to £800 [ if their bill was correct how can they reduce it by £1000 ?] I paid this £800 by monthly instalments of£100 and the very day I cleared the bill I returned to British Gas, never again and if I am out somewhere and NPower have a stand/stall trying to sign people up I march right up to them and tell any bystanders why they should walk away and most do !