Billed for a contract that ended

My contract ended October 2017 and I asked Telkom to cancel the contract as I didn't want it renew it. I sent a cancellation letter on the 4th of October 2017 which I was told was never received and thus my request was not actioned. 11 December 2017 I called telkom and was assisted by Zethu Benete who asked me to send the cancellation form to her and she would have it actioned and I should receive feedback in a few days. I sent the form same day and on 13 December sent her another email asking her to confirm receipt of my mail but she never rep****. Beginning January 2018 I went to a telkom store where they resent the form and told me I will have someone contact me in 3 days to acknowledge my cancellation request. That never happened. 05 February 2018 I called telkom once again and was told that the cancellation form was on the system but my contract was not cancelled yet. She told me she would escalate it and gave me her supervisor's email who I emailed and once again, I have so far received no feedback whatsoever from Telkom. I want telkom to cancel my contract immediately and reimburse me the money they have been deducting from my account since November 2017. And I do not want any more debits from my account for the expired contract.