Money debited without any prior arrangement

Yesterday I woke up to realize that R800 had been debited from my account from FNB personal loans without any prior arrangement, as a result some of my debit orders didn't go through. I called the call center iwas told to call *** and on that number you wait and wait and no answer. Then today i called to the loans department and was told it cant be reversed but I was never told about this arrangement. So I made a new arrangement with the consultant for next month moving forward. I want that money reversed today, I was never informed!