Failed by my trusted bank - FNB

Around February of this year, I lodged my complaint for unauthorised debit orders which amounted to +- R4000 which date back to November 2016 on my cheque account with FNB. At first, when I visited the branch at Maponya Mall, I was advised to merely reverse the debit orders. Obviously this meant that I could not reverse as far back as 2016 which is the date where this problem started. They only allowed me to reverse as far back as 40 days. Since then, my visits to FNB have been met with so much unwillingness to help me. They don't bother to keep me posted on the progress of the case and every time I go there I am told that the ***** department is still investigating the case. I would like my trusted bank to advise me who authorised these debit orders and to give me all my money back.