Blacklisted for an account I do not own

About 4 months ago I started getting sms's telling me to pay my account and a reference number. It did not even say who I own this money to or how much I am suppose to own.<br> After a while my phone rang and then there was a voice message saying the same thing as the sms's<br> There was a telephone number to phone - the number does not exist.<br> Then the calls started. <br> When the calls started I was told it is Nashua Mobile's lawyers. They could not tell me how much I supposedly own Nashua Mobile. The moment I tell them I do not own an account they cut the call.<br> During one of these calls I asked the guy to please send me an e-mail with all the details and the account they say I own. He sent an e-mail. No account, no sum of money I own. Just this. Please pay your account to avoid legal action. Ref number and their banking details.<br> I had an account with them in the late 90's early 2000 - but I do not have an account with them now, nor have I had one since about 2002. My credit record was clean - now they blacklisted me. I have a contract with Vodacom for a couple of years now and it is always paid. Please Stop the harrasment and remove this or I will go to the ombudsman