FNB charging me interest for late payment even though they are the ones that messed up

<p>During the month of December FNB Homeloans debited me twice in one month. on the 20th and 23th of December. </p> <p> </p> <p>I reversed one amount around the 24th of December. </p> <p> </p> <p>They then reversed the other amount of the30th of December and it looked like i did not pay at all . </p> <p> </p> <p>What i hate is the called me and sent me endless messages saying i did not pay even though it was their mistake . they did not even apologise for their mistake. </p> <p> </p> <p>The lady who called informed that i was still going to be charged interest for late payment even though they were the ones who messed up </p>