Multiple phone calls each week

I have been called by the same telemarketer from "Security Promotions" at least 15 times in the last two weeks.  I have asked to have my phone number removed from their calling lists at least four times and asked them to stop calling me.  They are still calling and sometimes they just hang up after asking me "How I are you doing today?" and I reply "Fine".  This has become a form of harassment in my opinion and I would like them to stop calling.