Over charging

Telkom has been billing me for years for a 10m adsl line. Our area only has 4m lines. I have complained numerous times, and every time they admit and that they will get someone to investigate and then contact me afterwards. But nothing ever happens. Recently we have also been complaining about the line going dead at about 10pm every night. They send someone out at day time when everything is working, so that never gets fixed. Plain and simple, pathetic service