Solve this problem with a SILENT ring tone.
To do this use the record option on your phone. Record SILENCE for 1 second. Save the phone number that you want and assign the name "Do not answer". Assign the silent ring tone to this number.

After that when they call you will not be bothered because you will not hear a ring as it is silent.  The only way you know they called is when you look at your phone and see that you missed a call. When you see the missed call was from "Do not answer" you can just laugh.

Does not block the call but otherwise solves the problem.

Got a phone call from an out-of-state number
that I don't "know" or recognize.  
I didn't answer, but looked up the number here.
They left no message.  

I am on the National Do-Not-Call List,
and have been for over a year now.  
(I guess this is our government at work for us.)  

I'm going to http://www.fcc.gov/complaints 
AND to

https://complaints.donotcall.gov/complaint/complaintcheck.aspx
and see if that can get the government
to work for me, and stop these calls.  
(Yes I will go through all those steps.)  
[I have also bookmarked these URL's.]

This credit card peddler is going to get billed for wasting my time

They call me everyday three times a day. So sick of them.

I bet they call me 50 times a week for three weeks now.  I am on the freaking no call list.  Why doesn't the government crack down on these outfits!  If I want to do business with someone, I will call them, otherwise respect my privacy and leave me alone.