MTN moemish

So early on this year March I got my account billed by MTN for reasons that I do not know. I have no contract or SIM number with MTN. I still do not know what they billed me for or where they got consent to do so. Now its end of July and my credit score reflects negatively that I am in areas with MTN. Like for real?!! I have no business with MTN whatsoever and the last phone contract I had was with Vodacom. Trying to get this cleared is another nightmare. I went to the nearests store and got given a number and told I would have to be very very patient because they take very long to pick up. So could this be another tactic to suck airtime money out of me? So the store wouldn't help me now I had to do an affidavit at the police then cue up on the call which never gets picked up as if I have nothing better to do. In the meantime they are messing up my credit score. Well done MTN!!!