Bad service

I took a 24 months contract with Vodacom in 2018 December,,last year on the 2nd November i called then to give notice for cancelation since December was gonna be last moth month of the contract, i called again 14/12/2020 to confirm that my contract will be canceled end of December 2020 i was assured that it will be cancelled, to my surprise it was not canceled they loaded airtime to my number as usual 01/01/2021,i called them 02/01/2021 to find out why contract is not canceled i was told that tha consultants i spoke to in November did not log my request properly on the system as a result they will debit 25th installment this month the contract will only be canceled end of this month, i am not happy with the service and i don't want their incompetence to cost me the money i dont have