Quick to take money, No answers when questioned

I Upgraded my package on the 8th of September when the upgrade as due. I knew the amount I was going to get billed and had no complaints regarding that, yet when I received my invoice due, the amount was in fact DOUBLE the amount I needed to pay. I questioned that immediately and was told that because I received the handset on the 8th I was liable for a Pro-Rata amount from the 1st to the 8th. once I requested my statement, it showed that the device costs are R600 for the month, and R400 for the package (deal) I was on. all that was still fine until I realised the Pro-Rata amount, was in fact the full amount.. I had been charged the full amount: R600 for the devise and R400 for the package I was on. There was no Pro Rata amount. I had to pay double the invoice for the first 7 days that I did not even use or have the device or package.. That is honestly unacceptable. and when I contacted the call centre for the third (3) time I was told the matter would be escalated to the accounts department and I will be called in the next 72 working hours ( as if 24 or 48 hours waiting for an answer isn't enough..) Today is however a week after I had been told I would be called within 72 hours..