Incompetance on Staff and Mangagement

I have been receiving calls , sms and emails from Nu -debt , they are rude, *********** , anyway they say I owe Nashua Mobile R18000.00 going back to 2003 which 13 years ago , I ask for proof of contact that we signed. so that I can see if it was us , due to a lot of ***** going around , I get answers Like Eish . mmmmm. you owe them the money pay up , or your are denying your debt and this goes on everyday , I have even phoned and asked to speak to the so called Managers - no return phone call or email , and so it with a so called Vodacom account as well, I have been receiving emails from a Mr Brian Blignaut SNR . even worse all he does is send the same email every month . I think this is a disgusting way to handle your business