Cell C is taking more than I signed for

I use to have a contract for my wife with Cell C. The contract ended on the 7th of July 2015 with no outstanding amounts owed to Cell C,<br> <br> This morning I received an e-mail from Cell C stating that I need to pay double the original installment even after the contract has expired and i have payed all outstanding installments.<br> <br> I phoned the customer care center but they keep telling me it is because I bought additional data bundles in array (I don't believe a word of this). Every month when a bundle was bought I had to pay for that bundle within the month it was purchased, and now after the contract expired, now I have to pay for some phantom outstanding bundle purchase. I am not going to pay for something I did't get to use or that I never bought.<br> <br> The phone was disabled and was made a standard pre-paid account. All previous bundles were removed and all minutes were removed off the phone when this disconnection of contract happened.<br> <br> This is true ****************.