TELKOM keep on taking money for more than 2 years after contracts was cancelled.

In October 2016 I've canceled all my accounts at Telkom. They've been provided with all the necessary documents on several occasions. At the time I had a credit of more than a R1000 with them.

Ever since then up to January 2019 they are still deducting money from my account. I've tried to stop the debit order but Telkom changes it every month and keeps on deducting money. My bank says they can't do anything about it. Can someone perhaps tell me how can I stop them from taking money from customers without delivering a service? I have tried everything without any luck.