Interest upon interest

I got a loan from African bank in August 2022. I have been paying my loan and last month I decided to pay about R111000 and my balance was brought to about R143000. Now I am noticing on my statement that the interest has not gone down I am still charged almost R6000 even though my balance is less. Secondly, I have seen interest on arrears on my statement previously and it has never been more thatn R120. This month I see R2317, why do I have this? This means my instalment will not make a difference as when I combine everything including insurance my balance will never go down. I am starting to thin African bank wants me to pay for this loan for the rest of my life. Please explain the interests. This is when I wish I had a lumpsum and just close this and move on with my life.