I just joined Bulb after having lots of grief with Npower, my usage is less then £600 per year but still they increased my direct debit from £70 to £107 per month! I complained and got no answer!!! I`m in credit again with £172, prior I had £300 + credit, I hope I`ll get it back after the switch!
After reading the reviews on the internet, I decided to join Bulb, wich I advise you to do the same :)
bulb.co.uk/ refer/doinita