Vodacom customer harassment

I had a contract with Vodacom mobile which was about to expire in September of 2023. I called them multiple times to notify them that my contract is expiring in September and should be terminated. The lady on the other side of the call promised me that the contract will be terminated and no more debits will happen after September. However in October a debit of almost double the contract debit went off. I went to a Vodacom shop to complain and the employee just said that is corporate for you. And I went to my bank to reverse the ******* debit order. Since January this year I have been harassed by debt collectors sent by Vodacom. And when I called Vodacom customer complaints, their employee acted as if they were assisting me and at the end of the call gave me a number to call so i can get resolution of my problem. When I called the number it went staright to the debt collectors sent on me to collect an ******* debit order which was deucted after the contract has lapsed and the value was way more high. Where can i get assistance to resolve this matter ? I even involved my lawyers, this is corporate harrasment at its worse.