Interest charged on settled loan

I’m quite saddened by the results of how you guys operate.

On the 24th of June 2022 I requested a settlement letter from you guys giving me X figure if I pay before or on the 1st of july 2022. Payment was done on the 25th of June and already on the 26th of June the account was showing a balance of R0. According to my knowledge, you guys wouldn’t need to charge me interest or assurance or even admin fees, but yet here I sit with a balance of Y even after I’ve paid you guys off.

This is absolutely pathetic from you guys. Funny enough, I found my slip of opening my first account with you guys in 2007 that my parents helped me get, think 2022 is the last year you guys will see me as a client.