Harassment from Standard bank insurance brokers

After my worst experience with this broker firm,where I lost such a lot of money, they have the nerve to keep on calling me ,to get more money out of me. The more I told this call center agent that I'm not interested, the more she insisted to explain me their latest money making scheme. The more I told her that i don't want anything to do with this broker firm the more she wasted my time. What can I do to stop this company harassing me,with their products? I don't want anything from this broker company. I'm a client of Standard bank South Africa and I want my privacy to be respected.