Unfair bank charges during the month despite account in good standing

This month (mid month to be specific)i was unexpectedly charges bank charges during the month by FNB. This means in a period of 2 weeks which was in the month of July and early August. I do not know what these charges are are for. I logged a call with FNB and provided my details and this is the reference number (R***) and i kept following up and nothing has been done and i have not received any explanation. I find this unacceptable because FNB calls immediately and sends message even if i owe R5 on the account but now they cannot reverse an incorrect amount charge when im on the right