Bad after sale communication and problem solving for paying customers

I bought a 2020 Isuzu D max from Middelburg Isuzu and my car that I traded in was not settled in time and my instalment went off at my bank. I notified the sales ladies as well as the lady working in the finance department . They paid back an amount R635 less than the installment that went off. This is now two months after and after numerous calls still nothing I feel that they were quick to sell but their customer satisfaction sucks badly. If I am allowed to state names please let me know