incorrect debit order date resulting in unpaid fee

I would like to lodge a complaint with regards to the debit order that was processed on my account for the incorrect date and due to this I was charged unpaid fees on my cheque account.<br> <br> The debit order agreement was for the 25th however the debit order was processed on the 24th .<br> Now I am getting sms's from the debt collectors for non payment of the account and this is a bad reflection on my credit report<br>