They keep calling all day and something at night.

First, I am on DO NOT CALL. Received a call today at home.  Said something like children's cancer society, or something about children and cancer.  As this is almost always a scam, I said "no thank you," quiet for a few seconds and then they hung up without saying a word>

They continue to call even though we have said at least 100x we wont contribute

Shows up on caller ID as "AA" - I didn't answer, and they hang up when they realize the call is going to the answering machine.  Sometimes they call often during the same day, and sometimes once every few days.