I have been harrassed for the debt I dont have

I received messages and calls from vvm telling me to make arrangements for payment of my telkom account. I told the consultants many times that I do not have telkom account or any phone account. They told me to send my proof of address and affidavit via fax and they always promise me to send their fax number via sms, but instead of their fax number I still receive mesages for payment arrangement and failing to do so they threaten to take a legal action. I am tired of being harassed by vvm because one consultant will and you explain your self next morning the other will call. I do not have a telkom account or any phone account I am using prepaid cellphone