Appalled by multichoice

I had the most appalling interaction with dstv this morning. I had a guy call me selling insurance. Something about insuraning my decoder. I explained to him that I'm not interested and explained to him why. He went on to say that I wasn't making sense. I told him that it didn't have to make sense to him, I'm not interested. He wanted to continue explaining about this insurance and I told him not to and hung up. I thought the ordeal was over but to my surprise he called again. He practically was forcing me to listen to him and to take up this insurance. Once again I told him ,no thank you and hung up. He had the nerve to call the third time wanting to explain again. I am truly disgusted by this and never want to go through that again. I felt harassed by this guy as he kept on calling. I thought after telling him I wasn't interested it would be over. This made me uncomfortable and I felt forced to listen to him even when I didnt want to.