I'm really fed up and disappointed with cell c customer center incompetency

The cell c customer center consultant does not do their job correctly, my mobile router contract expired in September 2020 and I called in October 2020 to put a 30 day notice to cancel the contract and on the 15th of November 2020 was supposed to be the last debit month. To my surprise I was debited even in December and I called in they say the contact was not canceled by whomever I was talking to and the lady said they will cancel, to my shock I called in again in January 2021 I was told that the contract is still active and I should put a new notice to cancel, this means the last debit order will be in February 2021, this means I have paid 3 months just because of people's I competency at cell c