FNB personal loans premium

I had a personal loan with FNB. My monthly premium was scheduled for the 27th of each month. On the 26th I paid the amount, with interest, in full. I called FNB personal loans three times and spoke to three different consultants who gave me different information. The premium, with interest, was still collected on the 27th despite the loan being fully paid. I want the premium with the interest reversed.