Telkom is filthy

I have a data contract with Telkom and have been paying R249 per month until when my billing changed R388. I called to enquire about it in February and an agent advised that it was due to a Netflix account which he would cancel but that was never done. Long story short, I stopped paying the account because I was being charged for a Netflix account which I was not being using and later they went on to debit my account on a random date that is not a date which is on the agreement between myself and them. They then charged me R202 for reversing the money debited - my question is, is this practice from Telkom legal? FNB charges R120 for returned debits, so how does Telkom then charge R202 for a returned debit and more over they charge that fee upon a date that was not agreed on.