African bank harassment for loan paid up early

I took a personal loan in 2015 Asked consultant if I could pay it early as I did before , she agreed there would be no penalty. To date I receive calls for interest of r70 000. My loan was 62000 I paid r72 000. By the first year..I get calms now asking for interest owed. This should be prescribed and is unfair as i paid more than my loaned amount. This bank is wicked.i paid up my loans twice before and was not charged additional fees was not harassed like this. Please I need help as This is prescribed debt as described in national credit act.