Wesbank refusal to admit mistake

After being in an accident in September 2018, our insurance settled the outstanding amount owed to Wesbank on our vehicle finance in October 2018. However, even after the settlement amount was paid, Wesbank still deducted the usual premium amount from our bank account and refuses to pay it back, since their statements shows our account was only settled in March 2019. We are paying for Wesbank’s incompetence to allocate the money paid by our insurance to our account, because our insurer apparently used an incorrect reference when making the payment, although they sent a proof of payment to us and Wesbank, when the payment was made. After numerous emails and communication, we went to Wesbank’s offices in Menlyn in March 2019 and the person assisting us, confirmed that it was clearly a mistake and promised to send it to the correct people to have it rectified. He cc’d us in his correspondence, but to no avail. The only thing that happened was that his email address was made inactive and we could not contact him again. Now, a year later, we still get the same answer on all our correspondence. Even with clear documentation showing that our account was fully settled, as per the amount quoted by Wesbank before the date required for payment, another amount was taken from our bank and Wesbank insists they owe us nothing.