FNB hold payments back to purposefully hand clients over to lawyers

So I December I made use of Fnb’S temp loan feature in which you borrow an amount and it get automatically paid once fund are available in your account. As such by the time I got paid in December I expected it to be paid of and finalised. Low and behold in March I receive a phone call from Fnb regarding this same loan stating I owe an amount completely different to the original amount I took out. After some debating and me trying to ask why this was not taken care of in December,(or any of the subsequent pay dates after that) I try to get the lady to call me back on the next pay date so I can try to settle the account or make a payment arrangement. My next pay date comes around and I don’t get a phone call back or any correspondence. Then I get a sms from a lawyer saying that I refuse to make payments and they are taking legal action. It is important to note that this is an automated loan that you CANNOT pay through the app or online by yourself. So I make contact with the lawyer and plead my case and we get to making a payment arrangement which I finally get to pay. So now I have asked Fnb to please assist me with finding out what went wrong with the loan and why it wasn’t paid because it is evident that there was more than enough funds available. Fnb refuses to contact me regarding this and have instead listed me on ITC for an issue that I could never have resolved myself. They refuse to give me answers and are personally attacking my credit for something I did NOT do wrong. I can no longer apply for credit anywhere because of this issue and they refuse to contact me or give me answers when it’s clearly their system that messed up and they purposefully held back payments to make me the client look bad to cover up their systems error. The jest of it is I took out a loan, I made funds available for Fnb to settle the loan in the time the contract states I should, Fnbs systems needed up so they made it impossible for me to know about it so they can force this to some legal channels and make me Look bad and now I can’t get credit because of there mistake