Why can't Cell C explain my bill

We have two lines with Cell C for many years now. It was taken out by my mum many years ago. Since she is no longer working, we pay cash monthly. We have one line that's a top up 50 and a top up 100 @ R87(incl. Bis) and R109. I have been paying cash for more than two years now. Previously, they did not allocate one payment and I could not find the deposit slip so I paid the amount again. All was then in order.<br> <br> After this situation, I have been making EFT payments from my account monthly with the proof of payment emailed to [Email Removed] Total due was R196 however I was paying R200. This month I paid a bit late, the morning of the 05th August but at lunch time the two lines was hot lined. We call in to customer care that evening only to be advised that the account is R100+ in arrears. After a bit more explaining, it was found out the subscription had increase in February by R11. Understandable, however that doesn't add up to the arrears amount. The second thing, why wasn't we notified about the arrears on the 1st month and the lines blocked? The agent sent me the invoices as we don't receive them but these already have an arrears amount before the increase.