Harassment by Vodacom

Sometime ago I received an email for collections from Vodacom saying I have an account with them. I rep**** that I did not and that it was **********. I received a second email with the same content and I responded the same. Yesterday I received a call and they claim that I had made a payment and that I recently made arrangements for a payment with a call center agent, which I never did. I started all of this on that call and asked them to go back to their recorded calls to trace it. Today they have called and texted me about the same issue.

THIS IS NOW HARRASSMENT and if it does not stop I will take my own action against them for harassment.