Reversed Credit Card Payment

I am currently running in circles trying to solve my problem and am getting nowhere. Background: I have a Namibian Nedbank Visa card and have signed an APO form to agree that payment automatically be deducted from my South African Nedbank current account. Upon receipt of my credit card statement for January 2015 I noticed that the APO payment had been posted to my account on 21/01/2015 but reversed again on 26/01/2015. I have spoken to Patrick in the Namibia card division who referred me to Willie Hansen. I have tried to contact Mr. Hansen on a few occasions telephonically but he was not available. I have sent an email to Mr Hansen, stating my problem but have not received any answer yet. My next try was to email my problem to the card division email from where I receive my statements - to no avail. Trying to contact RSA card division results in me being transferred from Peter to Paul until eventually I am cut off.<br> I would like to know why the payment of my credit card account has been reversed despite having had ample funds in my current account.