WServe, Ltd
Constant sales calls

This companies keeps calling 5-6 times per day wanting me to give them money so they can show me thier designs. I have repetly told them im not intrested but they keep calling. Have asked to speek to the manager but they say there is not a manager there. They just wont take no for an answer. if you hang up on them they just keep ringing and then hang up when you answer your phone. How can i stop them??? they use a withheld number to call you.