Incorrect settlement amount given

I'm so disappointed with Nedbank, I called on the 01st of December requesting a settlement amount as I wanted to settle my personal loan and I spoke to one of the agent who told me the settlement amount was R2249.99 I requested her to double check and she said indeed that was the amount and an sms was later sent as a confirmation.

She advised me that once the debit order goes off on the 24th then I call in to cancel the personal loan so it can be closed. To my suprised I called in on Monday the 3rd and I was told I cannot close it because there is still an outstanding amount of R600 which I was not aware and when I asked where is it coming from I'm told the agent made a mistake and now I want this sorted because I took my time to call you and I kept asking if the amount is correct Maybe if I was getting statements I would have counted myself but nonetheless I want this account closed immediately I have tried to lodge a complaint with nedbank and I was told by Mthokozisi that the account is still active and they were still going to debit yet I told them I wanted my last debit order to be in December. This service is really pathetic