Upgraded but still being charged for previous pack

My new contract is the EPIC Top Up 100 @ R179.00 p/m.My old package was the Blackberry Exclusive Q10 package for R426 p/m. Old contract ended 8th February 2016. I upgraded already, but they still bill me for the entire February for the old contract. I should be billed PRO- Rata from 1st- 8th Feb for the old package and then from 9th Feb to end of February for the new package... I will NOT pay for the entire old package at that huge price when my new contract kicked in on the 8th February 2016. I spoke to an agent on Friday morning and could not get it through to her that THEY had made a mistake with the billing. I then asked to speak to her Supervisor and was put on hold for a very long time (From my Telkom line) at which point I had to end the call. Nobody has since called me back to discuss the fault in Billing. Cell C I have been a very good client and dont deserve this.<br>