Frustrated with constant calls

I have received multiple calls from Vodacom contracts departments trying to get me to renew my now expired contract. Each agent has been told that I do not wish to renew my contract now and I will contact them when I am ready. After the second call, I have clearly told each agent to please remove me from the list as I do not wish to be contacted by them.

Today I received yet another call from Sheldon. After telling him to stop calling because I do not want to renew now and to indicate this on my profile he decided yo respond with... well another agent will call you because you're so rude.

Seriously Vodacom? Is this the service you give customers? I still pay my bill, it's just not a long term agreement and it doesn't include a handset fee. What gives you the right to harass me with these calls after I have asked you to stop and then tell me I am rude because I don't want to talk to your employees?