Blacklisted by Telkom after my contract ended July 2019. What do I do?

I have been blacklisted by Telkom after disputing their debits since last August.

I had even gotten a call from them asking me to move to a month to month contract but I was already tired of them fluctuating my debits monthly and wanted to find another ISP.

My contract with Telkom ended in July and further, my router was disconnected from then. In August through to October they kept on debiting my account to which I would visit a Telkom outlet to ask them to close the account and then would dispute the debit at my bank.

This year February, they debited and I disputed it once again.

Now, I have been blacklisted by Telkom for a service whose contract ended and which was no longer active.

I need help in ensuring that my name is cleared.