Debit order for No Service!!

We have been trying to cancel a contract since early 2020. Only realised last year that they were still invoicing us for a line which was not in use. After numerous phone calls and each person telling us the contract is cancelled no more invoice, we still get it. A year later we are still getting debit orders off. Come on Telkom you can do better. I am extremely disappointed and wont be upgrading with you guys anymore