Nedbank incompetency when changing

I was approached by Nedbank to switch my account from Absa, after they came with brilliant offers, and reassured me that it will be the best move. I was hesitant, because I had a previous bad experience with Nedbank after they failed to debit my credit card from my account, and ended up having a skipped payment on my credit profile, even after I transferred the money to their account. This time, Nedbank assured me that the debit order switching will be a fast and smooth process, I only had to make sure my December salary gets paid into the new account. Cut to the chase: my debit orders didnt go off as planned, I am getting threatening sms from NEDBANK about accounts being in arrears, in the meantime its their fault I am in trouble, by not communicating, not advising me to transfer money to the old account because of the debit orders. The problem I have is the lack of communication, and also the promises that was made. I am getting declined for credit because of the loan instalment that did not go off in time. This is very upsetting, their consultants could only apologize but no-one could come up with a solution