Unsolicited Harassment

My boss recently received a call from DSTV Life Insurance. He declined cover but since then he receives nothing less than 30 calls a day from various numbers for DSTV Life. This is unsolicited harassment. I have lodged a complaint directly with DSTV telephonically with reference ***5. I have also reported it to the National Consumer Board but the calls have not stopped. Yesterday he was called again and the lady refused to tell him what the call was about until he gave her his name. When he refused, she dropped the call. I have a whole bank of telephone numbers all linked to DSTV Life that have been calling (which I have reported). This is totally unacceptable.