Nu debt

So I've been going in and out of mtn store and phoning numerous times and actually nobody can assist with closing the account ( the account has been closed for more than a year ) then the next thing is that I get emails from these nu debt agents demanding some money ( wich I settled on my behalf and was promised that account is closed and all is settled ) then i email copies of pop and email and write on whatsapp to this company requesting them to keep to their side of the bairgan to finilize and close this account , all of a suden I get new emails from nu debt stating I owe more money and acount is in areas ( a month later ) how do I even go about this ?

I have told them I will not pay a cent further and I am willing to go to court due to this matter as this is sickening to me how the can just support this *******ion

I have worked so hard to keep my name and account in clear but couldnt care if the mark me or flag me This is so upsetting