Cancelation of Contract

<p>I Contacted Cell C to cancel my account while it was not up to date in payments. I was informed that my notice will be processed regardless of my account being in arrears. My account is up to date and I decided to call Cell C today to verify my account will Cancel on the 19th of December 2016 and I will continue on a prepaid contract with them, I was informed that there is no record of my notice and since I was behind on payment they cannot create a notice to terminate. How legal is this? In normal human terms how if you are behind on payments and you want to stop those payments from affecting your situaiton in a more negative manner how are you not able to stop that account from continuing even at the end of your contractual obligation? Why I am supposed to provide 20-30 days notice only when payments are up to date and not at anytime? Why can I not cancel my account without any notice since the initial period agreed on has lapsed?</p>