Still worst service

This is 3rd review and still nothing done or fixed, paying for 100mps line and receiving now under 10mps. I cant work or do anything online as network always hanging or to slow. I ask why do we pay for fast up and downloads if we not receiving anything. When you do get through to their call centre all they can say is to reboot and check again and stay on line till signal beter but next day its back to below 10mps, can we start getting credit for MPS we not getting.