******** deduction after timely cancellation in advance!!!!

I was a satisfied Vodacom customer as i had two phone contracts and never experienced any unacceptable service from them during the course of the contracts. As i reviewed my budget, i had to end one contract as it expired August 2017. I contacted the cancellation line well in advance at the start of Aug to confirm that i will not renew it. The agent assured me that it will be cancelled upon the last payment 1 Sept 2017 ,where it qill switch to prepaid and that i did not need to follow up via email or any other method. That only the one contract will remain as i instructed. Well, Vodacom DEDUCTED AGAIN 01 OCT 2017, i contacted them when i saw the future dated payment which they *******LY loaded on my peraonal bank account....call after call was logged and again i was assured that its now cancelled and i will be refunded and the financial department will get in contact. None of it happened!!! And MY VODACOM shows that im not in credit via statement and no payout had been made!!!! I wish Vodacom had no access to my bank details as what they are doing is ******** and defnitely *********!!!!the agents cant assist, can someone with a tad of intelligence contact me for a solution to this awful error in your side!!!! Without false promises and assurances but actual results!!!!