A once happy customer is now irate

Having been happy with my 10G internet package with Telkom I decided to upgrade to 20G. After making sure of the facts interms of increased costs with Jeanette at Telkom Rosebank shop I went ahead as instructed and requested an increase in my cap which I was told would be another R50 on my bill. I am an existing customer so was expecting a bill of R450 at the end of my first month but instead I recieved a bill of R918! I queried the bill at the Rosebank store and no one could explain adaquitely why I was now being charged so much more. I lodged a formal complaint and was told I would be contacted within 7 days. That was 1/5/2015 and I am still waiting for an answer. In the meantime I have just received another bill for nearly a thousand rand. When I contact accounts they say it should be R450 but apparently not and no one at Telkom cares or could be bothered to get back to me. As I stupidly moved my cellphone contract to them and their cell data simply doesn't work I'm stuck paying these massive bills to keep my cellphone operating on my home wifi, otherwise I have no phone internet connectivity. No longer a fan Telkom!!!!