Chage Debit order details

I called toward the end of Feb 2014 to have my debit order bank details changed from Absa to FNB as I am closing my Absa account.<br> <br> I was advised that the debit order has been changed and will take effect immediately. However on the 1st March the debit order still came off the Absa account. This is understandable as I called in quite close to billing date.<br> <br> However, now 1st April the debit order again went off the wrong account. Since I am closing the account there are no funds available and now the debit order has rejected.<br> <br> How difficult is it to change banking details cell c? I am paying unnecessary charges on the bank account as well as rejection fees.<br>