Arrears on my personal loan - not my fault!

i have a query with Nedbank going on for 3 weeks now. I received a message in Oct 2017, thank you for being a loyal Nedbank client, thank you for keeping to your payment arrangements, for future payment arrangement contact us, so i did, just to find out what the message is all about. Before we wrapped up the call, the consultant asked if she can confirm my debit order date, i advised the debit day is still the 25th i dont want to change the date. For the month of Oct 2017 my account was not debited? And i was informed 2 weeks ago that my loan is 1 month in arrears? THIS WAS NOT MY FAULT! NEDBANK NEVER DEBITED MY ACCOUNT, AND NO ONE CAN TELL ME WHY? I HAVE BEEN WAITING FOR A MANAGER OR SUPERVISOR TO CONTACT ME, I HAVE HEARD NOTHING! i have been with Nedbank for 10 years, but if this is the service i get, i will switch banks!!!!