NSFAS failed to pay our fees after loan agreement

I graduated this year 2015 at Durban University of Technology,I did not get my diploma certificate because the institution said that I am owing,NSFAS used to pay for my fees and I signed a loan agreement.My account has been transferred to other people and they keep on calling me to pay the money even if I try to tell them that I have no money to pay because I am not working for now and my parents are not working,I tried to get help from NSFAS workers,they told me that fees were paid and now I do not know what to do because those people who are dealing with my account, they said if I do not pay there is an interest,I have decided to report them so that I will know why NSFAS did this to us after signing a loan agreement.