Built up a substantial amount of credit with e-on over a few years of them over charging me for gas and electric. When I tried to claim it back they made it extremely difficult, after speaking to multiple people over several months I did end up with it back in my account but it was extremely painful. On another property I had the same problem which I never managed to get back, they just send you round in circles with all their staff saying different things. The final strike was when their engineers came to fit smart meters and ruined my carpets. Stains left next to the gas and electric meters where they've trodden in something or spilled oil on the carpets which won't come out. Had nothing but issues with e-on and I wouldn't recommend going with them, I certainly won't be. After making a complaint about my carpets they've said they can't do anything about it and wouldn't accept any responsibility. Appalling customer service from start to finish.