Selfish, uncaring and inconsiderate bank

I took a personal loan with Nedbank and I'm currently paying an instalment of about R12,000 on the 15th of every month. I have never been in arrears. Today, the 14th of December Nedbank double-debited my account. A total of more than R24,000 was debited from my account. This is such an inconvinience. I do not even have money to pay for other debit orders this month and I will be blacklisted.