UNAUTHORISED DEBIT ORDERS

Two days ago I received an sms notification for R99. I had no idea what it was for, so I called Nedbank and queried. The information I got was that the debit is for SS Direct. now i have no clue who these people are, what they do and why are they '*****ing'my money. I got their number which is ***, i called the number there is no response. How can banks just allow these ********* into our accounts.