Money debited by staff with no explanation

R600 debited from my account, went to enquire and they agreed it was a branch transaction but no one could give answers. Said they would follow up and send the company details as they confirmed it was not a set-off from any of their departments (she phoned all credit departments while I was there). Head of Service Support was called but all she could say was her hands are tied. How can money just be debited in such a large company, manually by a staff member but can't be traced nor refunded? So much for TRUST and upholding the highest levels of integrity as per their \values"."""