Telkom not canceling Contract and still charge

I am very dissapointed in Telkom. I have cancelled my LTE contract in November 2019 since the contract was to end 31 Dec 2019. In 2020 they are still charging me and after numerous phone calls etc, they are still wanting to charge me for 2020 and I have not used any LTE data on that sim card since October 2019 as I had Fibre installed. Everytime I call, the operator states that they are escalating the issue and someone will phone me and to date, no one has still phoned me. I am reverseing the debit orders each month, which in turn, affects my credit ratings, due to the incompetence and greediness of Telkom.