UNAUTHORISED DEBIT ORDERS

MNMARKETNG / MN MARKETING / MNMARKETING have been deducting money off my bank account for months now, without my permission. I don't even know who they are. I searched the Internet to get hold of them and to put a stop to their deductions, but they are no where to be found. How do I stop them? Who are they? Do anyone have contact details for them please? Please help