If this is March of Dimes (which I believe), it's a shame--we may eventually have to outlaw phone charities in this country, if this type of disruptive behvaior keeps happening.
By the way, I DID call them back before looking them up on this site a month ago, AND I pressed '1' to remove us from their call list, and we started getting calls all week this week again.
So, I don't know if that works at all, but maybe sometimes...