Constant Harassment Over Baseless Matter

Who are these people? I have absolutely had them in chunks!! I am being harassed daily for an MTN account that I don't have!! More than 6 Years ago there was a dispute where my SIM Card was cloned and I was served with a R 4000 bill. For 2 years prior to that, my average monthly account was R 300. I logged a dispute in person at MTN and refused to pay until they could prove I had made calls to +/- 13 different African countries and that was that. Now these clowns pitch up and harass me in a very rude manner and threatening SMS messages. SIX YEARS LATER??? GO AWAY!!! From what I read here, I am amongst the many people you harass ongoingly.