MBD please stop harassing me!!!!

I have an Edcon account which I am in arrears on but made arrangements with Edcon collections. Now these people from MBD credit solutions have been calling me non stop claiming my account has been handed over to them, what confuses me is that my account with Edcon is still active and not been handed over. I'm really sick of them this is harrassment now because they would call on my cellphone, work phone with different numbers. Please help I'm sick of this