Payment required for non existent services

I have since received a call from Cell c who insist I pay for a fibre network service that was never rendered to me. I find this ********* that an organization would require someone (mind you I never have an contract or agreement with cell c but I’m expected to pay them R2700 for services not rendered. I’m told by the consultant that Cell c took over clients from December 2017 to supply fibre services at my previous of which I vacated in November 2017. Cell c has since blacklisted me these funds...to be honest I have R2700 but I think as a matter of principle organizations must not go into ********* behavior to raise funds. This is just unacceptable and don’t think consumers should be bul**** by companies.