Messed up finance department for VAF

On the 3rd of January my car got ******, thank you to king price for paying in time, the nightmare started when I had to deal with the short fall insurance Traffic. After a long fight they finally paid out, and standard bank gave me R8235,65 refund and a paid up letter. Four day's later they call me and say it was a mistake the payment was allocated wrongful I must refund back the money, I did refund the money back,now my account has an outstanding amount that needs to be settled, I don't have budget for that and won't pay for the mistake the finance department did,how do you do such a mistake? I'm very angry at standard to think my house is also financed by them, my kids will suffer because their finance department is a mess. I'm not taking liability for their mess