Unauthorised debits

I have been with FNB all my life but I am very disappointed after experiencing some ********** activity on my account. How did FNB allow MTN to debit from my account without my approval? What happened to security checks and verifications. How do I trust my banker to be professional if these activities are taking place? The banker on my app is never available which is bad as well because I pay for this service. I want all the charges to be reversed for all the disputes for MTN debits. And also need a serious and people focused banker who can help.