If Scottish Gas have checked the meters and this is what you do in fact owe, then I am afraid you are going to have to pay it. After all, you did use the gas during the 5 years. I agree that sometimes the bills can be a bit confusing though if you are getting both gas and electricity from them. I disputed a huge bill they sent me and they did investigate. They found that in fact I owed only half the amount they had asked for. While waiting for all this to be sorted, which took months, my bill grew further and - also being disabled - it was then going to be difficult for me to pay in one go. As I could prove that I am registered disabled, they gave me a payment plan that is really quite affordable. So, talk to them, they will try to help if they can. I should say though that I never tried to get out of paying my bill. It is after all my responsibility.