Telkom won't cancel my month to month LTE contract

I have a month to month LTE contract with Telkom that I just can not cancel. I used the MyTelkom to cancel the contract on the 27 Oct 2017. I received a call from one their agents in Dec 2017 to confirm the cancellation. The invoices just keep coming. Everytime I call they tell me that the cancellation department is has backlog. It's like they are just running the clock until they have made enough money.