Stop calling I don't want a contract phone!!!!

<p>I have been receiving calls from Green Connect with MTN offering me a a device on contract. </p> <p> </p> <p>I have stated aged time and again that I have no desire take out a contract phone yet I'm receiving calls sometimes even twice a day. </p> <p> </p> <p>Please make it stop because I don't know how else to say this. These people are a nuisance. </p>