Debit order canceled without permission!

Today I received a message from Wesbank that after paying a few payments towards a car I bought the debit order didn't go through this month as FNB canceled it. At FNB every person I spoke to said something else. Apparently only Wesbank could cancel it if the received instructions from me to do so. As I have no idea why the payment didn't go through I definitely didn't ask for it to be canceled! Why do companies like Wesbank and FNB make your life so difficult!? Everything was fine...and then they just make a mess. I want to know what happened and who made the decision to cancel the debit order as it could only be done by you Wesbank. And then your staff member still want me to pay interest because it was supposed to go off on the 1st. I look on the App, it showed it went off and were then payed back. Why???