failure to cancel contracrt

I had a contract with telkom mobile. The contract ended on the 11 Oct 2015. I used to pay R299 per month. After the contract was supposed to end, I began to be charged R550 a month. When i consulted telkom as to why the contract was not teminated, or as to why i was now being charged a larger amount witnout being notified, i was told it was my responsibility to cancel the contract before the end of the 24 month period. At the time of taking the contract this was not made aware to me. I went into the store and cancelled the contract on 21 october 2015. I have contacted the call centers 3 times since then and a month later my contract is still not cancelled. I currently have a R1000 bill from telkom. There call center personal are rude and incompetant. I expect better service and my account to be updated.