No voice or data connection / service

I am sick and tired of paying my bill faithfully every month but I have inadequate service from Cell C. For the last 3 to 4 months I've been completely unable to connect to the internet. In other words, I am paying for 1.5gb of data every month and I can't use any of it. It is extremely difficult to make a phone call, for the calls don't even want to go through and when they do, no one can hear me. This is totally unacceptable!