DMC is incompitent

My Name is Sello RAMPHENG id ***. I was offered a settlement for FNB loan of R1500 which i paid on the 12 April 2019 but the loan with Fnb is still not settle. When i call DMC for settlement letter they keep on saying they need to request a letter from FNB but how can FNB provide them with the letter because on FNB system it still shows an outstanding amount.......DMC please resolve the matter because i paid the settlement amount with you. I am not happy with DMC service..please resolve this matter.