Poor service- Failure to carry out debit order switching instruction

I contacted MFC to change my banking details and debit order date around the 15/08/19. I was informed that it was too late for the month of August but the instruction can be carried out from the month of September. I would normally make manual payments towards the car installment around the 20th monthly but to my surprise the debit order went off on the 30/08/19 meaning that I made a double payment for August. I lodged a complaint with Nedbank requesting a payment reversal for the unauthoried debit order that went off on the 30/09/19 as I had already made a payment and payment arrangement for the following month and the manager "Geoffrey Hirst" contacted me by email requesting proof of payment to process the reversal. That was sorted out but, my debit order still did not go off on the 20/09/19. I just received an sms stating that my debit order will go off on the 28/09/2019 meaning that the dates have still not been changed after wasting so much time speaking to one of their consultants telephonically. I believe these were very simple instructions and this is just a reminder of how poor the service is when it comes to Nedbank. This is one of the many reasons why I left this bank- failure to carry out simple instructions.