Unfair arrears on account

My nedbank loan was deducted this morning at 02h00, at 06h45 I received a message that it's over due. How is it possible??? I'm getting calls from Nedbank that I must pay but the deduction went off my account... I honestly think it's unfair and I have been extremely honestly with my payments. Nedbank must make sure I don't get additional interest cost or I will move my car and close my account and move to another bank.