I sold my car via absa fast buy and money was paid to absa on 29 November 2022

I sold my car via absa fast buy and money was paid to absa on 29 November 2022. I have been calling absa from the day they received the money and they confirmed they received the money but to my surprise every time I call to find out how much I must pay as was was told there will be discount on the shortfall I'm being sent from pillar to post Today is 10 December 2023 my account is still the same come month end they expect me to pay full installment.This is not fair on me as I've done everything they requested from me when I sell the vehicle and their customer service is zero they are not helpful at all. Everything I call customer care they give me number phone to call but no one answer those phones