ABSA Vehicle Finance

My car payment is around R4100 per month. On 1 Nov 2019 I have final payment on my car. ABSA debited my account on 1 Oct 2019 for R11 808.11. When I contacted them, they said that they never recalculated my interest when the interest rate went up and I now owe them the money. How fair is it that the staff is to *********** to do their job and now I have to pay for it. I am so frustrated. NOT 1 MANAGER WANTS TO SPEAK TO ME. Just shows you how bad it is, so they know it is their mistake so they probability want to keep me on a line and phone and irrigate me till I Pay!!!! Well you can take me to court ABSA. How pathetic. Just do your job and stop employing idiots!!!!!!!!!!!!!!!!