Settlement values that differ - AVAF

I am not happy. I paid a lump sum towards settling my vehicle and subsequent to that, I've had an additional 2 instalments go off my account towards the car. The banks app shows a settlement value but after calling them due to my dissatisfaction I was told that the app value isn't the same as what they see on their side and that I would have to pay an additional amount which is similar in value to the car instalment.

Why do I have to pay thousands of rands extra because your systems don't speak to each other? How was I meant to know that over and above the app value I had to call the bank for an additional settlement value? Fix this and close that account because I feel ****** as a customer.