HARASSMENT FROM TELKOM MOBILE CALL CENTER

Harassment from Telkom mobile call center agents. they call me 10 times a day. then one lady called me this afternoon, insisting that she WILL tell me all about the special that Telkom Mobile is running. i said i wasnt interested, but she insisted and insisted. please could Telkom stop phoning me. when and if i want something i will go into a Telkom store. How do i get these people to stop calling me??????