go into settings->call settings->voice call->auto reject and add number.you can also go to your call logs and long press on the number, and scroll down in the pop up menu to “add to reject list"
The case mate is mainly plastic, but has a aluminum plate on the back. I have had mine since I first posted about it a month ago. I have not lost any reception/had any reception issues since I got it. One thing I didn't like was the thin plastic bars...
http://www.google.ca/url?sa=t&source=web&cd=1&ved=0CB8QFjAA&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FCell_Phone_Freedom_Act_(Bill_C-560)&ei=TDzHTufHDYT-ggfAgqkz&usg=AFQjCNF6W-LNgM6ZiIN3JmsQc1xCNco9WQThey will unlock it, just call them.