Overpayment made by me

Hi. NCOs is a debt distribution service. Since October 2012, as per agreement i been paying R2400 per month to settle my debts. As per agreement my debtors be settled by May 2017. Its Jan 2018, and i still paying. Also one debtor has not received any payment for the 5 year period , despite NDPA having the correct details. This needs to be addressed ASAP as this amounts to theft