Unhappy Individual - Need to settle

I am upset, I had received funding back in 2012, they provided finance to me, once I completed my degree, no one had contacted me, couple years ago, 2014 or 2015 they had contacted me to say that I must make immediate payment or they would debit my account, I had provided them all the details but they did not debit, last year I had received an sms from debt tracker to say I owe them a certain amount, I had called last week and received the details for NSFAS directly, I had requested a settlement amount and bank details from NSFAS on an email, I had made a payment to them on the very same day and sent through proof of payment, I had on the email requested that my account be closed and a paid up letter to be sent to me, there has been no action as of yet, I have called through twice last week, but still no one seems to reply? Was I supposed to just leave the account and not pay it? Now that I have paid it, is there interest still going to be charged even though I have settled according to letter I have received? Would I ever get a response? The only person that I spoke to had provided me her email details but even she has not responded or got back to me? ***?

Please could some one look in to this matter and assist me, all I want is for this to be settled and closed, I will apply to study again! But would not apply to NSFAS and I advise no one to apply to this organization as it is very unprofessional with no feedback.