FNB - Bad Customer Service

Tried to resolve an issue where FNB deducted money from my account without notifying me of a deduction or what amount. Tried desperately to find out what the transaction was for - the transaction amount was over R 8,000 so was not small. They will not investigate it without me paying and additional R 37,00 fee for investigation. Why do i pay bank charges each month, and how dare they make deductions from my account without authorisation. FNB customer service is a joke and waste of time. Personal banker never returns calls and the FNB App - chat system is useless at the best of times. They clearly don't want my business and i certainly do not recommend them to any one else.