MBD harassing students about settled NSFAS accounts.

I am Nombulelo Makhiwane, with MBD reference n0: ********** ********** 82 being harassed by MBD through sms's for a debt I settled with NSFAS. MBD started contacting me a month after settling the account, when I told them I have already settled it, they instructed me to send them proof of payment and my ID copy, which I did. They never responded to that. I have sent these to them via e-mail twice, without response to it but a new sms telling me government contribution to universities did not affect my account. It is not government that paid, it is me, and I paid the amount NSFAS gave me as a due amount for my account. I need MBD to stop contacting me, before I sue for harassment.