Dirk:
Blocking does "work" if you have the right blocker.
We use a blocker that blocks ENTIRE AREA CODES.
Trust me - BLOCKING ENTIRE AREA CODES DOES WORK!
These CRIMINALS have never called me before but their number was blocked BEFORE THEY ROBODIALED OUR NUMBER because we have the entire 246 area code BLOCKED!
Have friends in the 246 - simply "invite" their phone number into your blocker - they can call right through.
These people are relentless even after they you have NO credit cards, they still call every day multiple times. Sad state of affairs in this country when this kind of activity still persists.