UNAUTHORIZED DEBT ORDER AT FNB BY GREYSTONE

Recently I received a call from FNB consultant to confirm a debt order from Greystone, I immediately inform them that I don't have any dealings/arrangement with Greystone, and what make me angry is that the money was already deducted and now I have suffered serious financial charges in an attempt to Stop the debt orders. I need an explanation as to who authorized this Debt Orders and what is the money for.