I've been told by a reliable source that when you push whatever number they say will stop the calls you are ONLY telling them that the number they called is a working phone number. It does not stop the calls.
Call your local resources such as Elders in Action which is a resource for the elderly in Portland Oregon. You can also call the senior center in your community; they would know who to reach to get assistance with that kind of thing.
They keep calling and asking for the last guy who had my number, who, I read in the paper, will be in jail for the rest of his life for repeatedly raping a nine year old girl. When I tell them that, they just keep asking, where is James B? One time when I asked for the supervisor, the girl said, he's slipping (sleeping with a heavy foreign accent). I suggest blowing a very loud whistle in their ear next time they call you. Torment them back as best you can. Losers.