Failed to deliver again!!!

After my previous encounter with Nedbanks bad service, I finally received my student loan settlement amount an i paid it the same day on the 13/11/2017. Two days later i phoned them to make sure the account was paid in full and they confirmed that it was. I asked for a paid up letter and the lady assured me i will get it the following day. Its been 13 days and i still haven't received it. Today i received a sms that an account i had with Nedbank more than a year ago is overdrawn, I phoned them and gave the account number, and it turns out that this is and account which i closed lats year round about the 06/2016, that's the time i moved to ABSA. The arrogance of the lady which helped when she asked me if i can prove that i closed the account is unacceptable. I was in the Tygervalley branch ti deactivate Greenbacks rewards from my Credit Card which i have with then, and the only account then was the credit card, my student loan and personal, of which i cleared my student loan. This bank is certainly not up to standards and they are running a poorly developed banking architecture/infrastructure.