Wesbank treated my like a ******** after being loyal and refusing to refund me

My late wife and I purchased a vehicle from VW and was financed by Wesbank,I was responsible for paying the account from day 1 , however my wife passed on and I continued with all the household commitments, this year I was left with a balloon payment, Wesbank sent their team to follow me around while I was busy looking for further finance until I got it in November and I settled the on the 27th November 2023 and in December the payment went through from my bank against an account that has been fully settled , until today Wesbank is refusing to refund me the instalment that went through in December, they demanded letter of authority ,settlement letters , death certificate and letter of vehicle transfer , everything was provided but the bank still has not refunded my money, imagine being ****** by a bank after being treated like a ***** , being followed around because of the balloon payment, I feel disrespected by the bank and its entire staff. @ Wesbank I want my refund with interest.