Horrific service from telkom

Hi there I have a serious complain against TELKOM. HOW DO I GO ABOUT THIS? PLEASE HELP ME... WHEN you phone there call centre that agent takes almost 20 minutes to half hour to pick up there phone. Eventually when you to.speak to consultant they can't assist u with ur query. I have major problems with my Wi-Fi and have tried to phone the technical department on several different occasions since the beginning of this year and still nothing has been done. CAN SOMEBODY PLSE ASSIST ME ON WHAT TO DO. THEY BILL ME EVERY MONTH ON TIME AND I PAY MY BILL ON TIME EVERY MONTH BUT THERE SERVICE IS TERRIBLE.