Dstv harassment won't stop

Have been receiving harassing phone calls from Dstv now for weeks where they keeping phone and when you answer the phone call just goes dead. This happened after receiving a phone call about some deal that they are offering and telling them that I am not interested and the guy being very rude about that and after that now receiving a phone call very day. Have called their customer call centre to complain as well and the phone calls keeps coming. Received a phone call from +*** after logding a complaint at Dstv. Does Dstv not have something better to do with their time than harassing customers who is not interested in their deals.