I had 2 accounts with Unifi, the first account I had R2000 left to pay it off and the second one I had R8000 still to pay by unforeseen circumstances I had financial difficulties to pay then I ask my bank to pay it off

I had 2 accounts with Unifi, the first account I had R2000 left to pay it off and the second one I had R8000 still to pay by unforeseen circumstances I had financial difficulties to pay then I ask my bank to pay it off. I requested settlement letters and they made a mistake with the amounts reflecting incorrect and my bank paid accordingly the settlement letters but later they come back to me to say the letters were issued incorrectly they insist I still owe them and they refuse to give me paid ip letters. I dispute to say is their mistake they must take responsibility and own up but the refuse to close my account.