Pay, Keep Paying and Pay some more

I cancelled a data contract with cell c on the 9 November 2020 and paid the cancellation fee. The fact that the person I spoke to did not do their job is now my problem. I received a bill on the 11/01/2021 I called again and asked why am I receiving bills for something I cancelled?!!!! Oh sorry we will cancel it now it is March 2021 and I am still paying for this cancelled contract. Not my problem fix it and refund my debit orders.