i've been threaten by this campany

I have an Edgars account I was in arrears for same time and Edgars handed my account to VVM, this VVM company never contacted me, I then went to paid the amount that was in arrears at an Edgars store only then did this company started sanding me sms's and phone calls threating to blacklist me if I do not pay. I called them to ask if they could stop with the threats and a lady by the name of Promise Ndlovu said they will not stop until the account is closed, I would appreciate if they could stop with the threats