Cell C Poor Wifi Connection

We have been having numerous issues with our Cell C Wifi Connection in Kraaifontein. Every evening from 17:30 - 19:30 the wifi is down. Cell C gives no explanation, only apolgies. In March our wifi was down for 6 days, also with no explanation. We pay for a full months service, which we do not receive. How can we get a refund for the time we did not have wifi connectivity.