12+ months and no response

I have been contacted by a third party (MBD Inc) chasing me for an amount on an MTN account that I do not have - and never had!!!

After submitting TWO affidavits and weekly chasing-up emails over the past year - to their customer service, info and legal department (and being provided with several reference numbers) I am still nowhere closer to having this sorted. This has no apparently affected my credit score.

There is no telephone number on which I can get hold of them either. Do I get in touch with the ombudsman???