Debit order when loan already settled

Cant get through to the telephone banking numbers, you just get automated voice note saying they experiencing high call volumes, when you get through they say you in wrong department and they re-routing you, very in-efficient bank although FNB claims to be the best bank in SA, they also debited my account although my loan amount was settled, very poor and un-professional services from FNB. Will not refer them and will look in the new year to moving to other banks.