Nedbank over debits my account again

Nedbank personal loans, keep over debiting money from my account. I have spoken to them countless times about this issue yet they continue to do what they want with my account. I have paid my installment for this month already yet they feel the need to debit my account again, R4932 on the 10th Dec, why would you do that? Who gets paid on the 10th really!

I wish they can resolve this unnecessary matter

Regards Jamal Thomas