I have recently changed my electricity and gas supplier through switch with which and thought that it would be good idea to highlight the positive experience that I have had. I checked it out because I felt that I was paying over the odds for my electricity and gas, and found a supplier that could save me around half of my current bill with Scottish Gas, and so I switched in October.
Earlier today I checked my online banking and found that Scottish Gas had repaid overpayment on my gas account, I called and tried to find out more about it (I hadn't actually been told they were giving me money) and they said that it was only for my gas and my electricity final bill would be out soon. My point? I got back over a third of my yearly bill! Some companies are putting up the payments keeping the money and pocketing the interest! Be aware that this is common practise with some companies and my families experience of Scottish Gas is that they have tried in the past, please check your bills and call the company if you think it is too large, check out how much you can save and let them know, you never know they might be able to match it!