Don't care attitude

On 14 September 2017 I was contacted by the Legal Department of Mtn which stated to me that I am owing the R 23 000. I nearly fell off my chair as I cannot remember that I ever had a Mtn number or for that matter a contract either cell or Internet with Mtn. I explained nicely to the gentleman, sir I don't have business with you, whereby he said they will sue me and issue a summons on me. Thank you for your time sir and good bye. No further details nothing. I cannot phone back nothing. So I phoned Mtn and inquire. I was told that ***** took place and I must hand in a affidavit and a certified copy of my ID to the nearest Mtn so that they can open a ***** investigation. At the shop I ask for copy of the contract and where did I sign for the phone. Nothing could be given to me. I asked but your attorneys will sue me while your inquiry takes place and my credit name will be affected negatively. the answer was well the process will carry on we will fix it later. If my credit name becomes affected negatively I will loose my job. So you leave me no choice but to get the assistance of an attorney. My income is important to me and so my name. No details can be given where the accounts were send neither the warning letters. You are treating me unfairly. The number in question is ********** 240 opened in Pine town Kwa -Zulu Natal on 13/12/15. I hope this matter can be resolved before I need to call an attorney to sort it out for me.