Bad customer service

My name is Nonjabulo Mchunu I had an account with MTN but the account was paid up and closed in 04/2017 by a gentlemen called Martin from Edendale MTN branch in KZN, Pietermarintzburg. But VVM is busy calling and sending me messages saying I'm owing MTN R8875.59. They are very much aware that a ********** account was opened and they have rectified and removed the hold on the account. I do not owe mtn a single cent and my account was closed, I really don't know where to go or whom to speak to about this matter as MTN IS BUSY SENDING ME FROM PILLAR TO POST ABOUT THIS MATTER, mean while VVM is saying I must contact MTN they are the one who have the authority to remove my name from them.Ive spoken to Lebo from legal department and basically just about everyone who responds to all my complaints but nothing is ever resolved. I am worried about that i will be black listed for nothing. MTN MUST REMOVE MY NAME AND SEND ME A PROOF THAT THEY HAVE REMOVED MY NAME FROM THESE PEOPLE because when ever I call MTN they give different stories, no one is willing to help me even though they can see on their system that I don't owe them and that this was a ********** account. When is the right time to put them through laywers? Every day i get messages and phone calls to send vvm my signatures to a fax number that doesn't ever work or an email that no one ever responds back to say the mail was received. What a headache it is to deal with MTN its been over a year now and no one is ever helpful. They respond to our complaints once and when you reply back you never hear from them. I don't think i can ever recommend anyone to deal with MTN . Ideally we should actually sue MTN dragging my name through all this had it not been for *********** staff who did not check the particulars of the customer properly we wouldn't be where we are. If anyone knows or has contact details of the Director or CEO Rob of MTN kindly provide them. Something definately needs to be done now about this.