Fnb bad service

i called Fnb call centre ,i spoke to team leader Evangeline Damons today,i needed the amount that i did not consent to be refunded in my account,i was informed i had arrears in April 2018,i ask why was i not called to make an arrangement ,team leader said i was sms and sent statement,i ask where is the arrears coming from,they said i did not pay an instalment due in April,i ask how much ,she kept putting me on hold to check after evry question i raised as if she is not sure where is the arrears coming from,she finally told me the amount am in arrears for is actually lesser now because there was money debited inbetween to lessen the amount missed,i asked why wait and not inform me then all of a sudden when Fnb feel like debiting the amount they just debitwith money i did not even budget for,Evangeline said it is Fnb right to debit outstanding arrears,i also work for bankong industry,by law you cant debit client money without getting a consent i want my money as i cannot have this money debited without me arranged for it,Fnb please stop this i need you to reverse this money ,proper arrangement need to be done with me after affordability and expenditure has been done i need justice ,you dont just take money without a client consent