Disgusting service from Nedbank

Nedbank!!!! .... Absolutely disgusted with the service, I have a debit for a loan which I never miss a payment, my debits go out regularly. Last month it was debited once again but I received a notification saying I have missed a payment which has now affected my credit score. Why have they taken my money and saying that I missed a payment and damaging my score? I tried calling the call center for help but because they have an old contact number they refused to update my current number and give me assistance so what do I do now?