Unauthorised Debit

An amount of R7467.46 was debited on my Business Cheque Account on 06/08/2015. When enquiring with the Merchant Help Line they advised me that the amount was debited by Firstrand Bank Limited. I was given a Number for a Desiree Van Wyk whom i tried contacting today - 12/08/2015. the number just rings and rings with no answer. I then went into FNB Clearwater Mall where an incredibly Helpful Lady helped me. I sat in the Branch for almost two hours with one consultant being pushed from Pillar to Post. We were given about 11 Different Numbers to try and trace the Debit which noone would take Responsibility. it then turns out Desiree van Wyk is on Sick Leave and noone is able to do her Job whilst she is not there. we then lodged an internal complaint as there was no end in sight. This unfortunately puts pressure on me because of the fact that I am trying to Run a business and I do not have time to run around after a bank who I trusted with my money. I would appreciate a Resoulution to this Complaint as soon as Possible.