Account for another person's telephone

During 2013 I managed the affairs of a business which traded under the name Woodworld, using using the telephone number *** for some years. To facilitate the payment of the account I went to the Telkom office at the Garden Route Mall in George, requesting the bill to be sent to the email address that I was using at work. I was asked for me name, ID and telephone number and subsequently the bill was sent to the correct email address and I could pay it in time. After a few months I left the business. About a year later it was sold and the new owner wanted to put the telephone on his name. He contacted me as they said that the line was mine. I gave him a letter to indicate that I had no interest in the telephone. Subsequently I am receiving calls on my cell phone from a certain Kobie van Wyk from *** indicating that I owe more than R2000 on that account. It was never my telephone. She threatens to blacklist me but never produce documents to prove that I was the owner of the telephone. If such a document exist, they made me sign it under false pretences. I have never seen this account either. I find this harassing and it should be rectified.