FNB should not tolerate any ***** and negligence happening in their institution

I'm truly dissatisfied with the service I've been receiving with this bank I had a joint account with someone it came to my attention after seven years that the person has withdrawen money without me knowing whereby we both suppose to authorize any withdrawals made, I've been going to the bank to seek answers but not getting any they don't even wanna give a account mandate print out and the banking consultant whom authorized the cheques, the bank told me to open a case at the police station which I did but they're taking forever to give the police that information because they said to me they can't give me the information because the information is the property of the bank which I don't understand because I'm a stakeholder in that account now that the case has been opened the feedback from the officer was his also waiting for the bank to give them information, it's more then six months now yesterday again I got a response from the investigating officer saying that the bank has lost the 203 documentation which I don't understand how, it's clear to me that something has happened and the bank is protecting themselves and the employee