Adamant SPAM calls!

I am soooooo sick and tired of all the SPAM calls from the Foschini Group. And the people are so damn adamant!! The one asked me why i am not interested and is said i am just not interested but she insisted to know why. Yoh i flipped and she asked me why am i going to on. This is not acceptable!! Im sick and tired of all these calls, and every time it for something different and if you dont answer they call and call and call. It is sooooo frustrating to say the least as there is other words i would rather use. How the hell did they get my number and why are they so adamant, i want my number removed!! This is utter bull ****!!