Nedbank daylight and exploitation

I took a loan from Nedbank in August 2019, my pay date changed in January and I called nedbank to inform them about the change obviously that was going to affect the debit order date, I asked them to change the debit order date n they have not changed it, the account goes into arrears every month and I have to phone every month to remind them to debit my account, the sad part is that when the account goes into arrears the loan amount attracts more interest which is not my fault and the interest added is not reversed, I feel like I am being exploited by Nedbank. It was my first time to take Allan with Nedbank and I experienced such a bad service.