Unauthorised service fees

I had two loan accounts with FNB. One has been paid up and the other one I have made arrangements to pay off the arrears. Since July 2021 my acc have been debited in the amount of R115 x 2 on the same day for a FNB loan service fee. I have made contact with the bank on 9 september 2021 and after 25 minutes no one could explain to me why that amounts have been deducted. Such *********** staff they have. I am sick and tired of this bank because they are *****ing from their clients.