Unauthorised debit order date change.

I have a completed my debit order authority form on 28/09/2021. I signed to have my study loan debited on the 29th of each month. Yesterday (25/11/2021) they tried to debit my loan and now it shows as an unpaid premium. I phoned Aphiwe Mbodla (who processed my enquiry) and she said that i need to phone the loans department. I phones the loans department and they said that i should speak to Aphiwe Mbodla. Now I'm getting a bad credit score due to their incompatence.