I am getting at least two calls a day. I have asked numerous times to be put on DNC

Received 2 missed calls from this number, when i called back, it's a Male Enhancement drug clinic or something like that.  I told her I was calling because I received 2 missed calls and she started trying to sell me something.  I told her 4 times that I wanted to be put on the DNC list and she just kept talking trying to get me to reconsider.  I had to literally make her stop talking.  Tell her to put me on the DNC list. and not bother me again.  Then she hung up.