Connectivity issues since day one...

I app**** for a Cell-C data contract on the 1/11/2015 (30GB anytime, 30 Nitetime) and from the start I have had slow download speeds and almost no connectivity even though my signal strength is 100% It is almost impossible to browse the internet between the hours of 17:00 and 22:00 during the evenings. I logged the call on reference number ***, I was contacted by their technical department and informed that the tower in our area was overloaded and that they are looking into it. It has now been 2 weeks and it has got progressively worse and worse. I am now paying for a service that is now un-usable. Please Cell C fix this!