as someone who did this kind of calling before, they wont care if you get mad. some find it funny even and may taunt you. it's all done via computer dialing anyway which is why you pick up to nothing. easiest thing to do is say "i'm not interested take me off your list." and let them hang up after a confirming. don't waste time with a sob story just the line I gave you and the call should be under a minute and shouldn't happen from that number again.