FNB early deductions without my persmission

Am so furious right now with this bank that is so inconsiderate to its clients. FNB just deducted loan installment today and am not even paid for the month of DEC . am chatting with their consultant as usual i cannot be assisted i need to call tomorrow . i need the money now . i signed up for this installement to go off on the 25 now is the 16th money is gone . no one gave them permission to do this .i need my money back