Standard Bank mandates without authorization, is that legal?

I am once again disgusted and disappointed in this Financial Institution. Standard Bank has taken upon themselves that they will mandate a debit order that I did not authorise. Is that even legal? Should there not be any form of communication before they do such? An email? Sms? I have tried calling their Complaints department with no avail. I need a reversal as of today. The financial institute has been paid last month(Oct). And has decided to debit again this month (Nov), the part that infuriates me the most is that they debited from funds that do not belong to. The owner wants they money back and I'm unable to send it back to them and is threatening to file charges against me. I need urgent response from this Financial Institution. With a written or voice recorded authorization of this mandate.