I have several ways of handling cold calls, most of them polite. I've just used one of my (usually) more successful ones. It didn't work.
Caller: is that Mrs Stott? (She's my alter ego),
Me: I'm afraid she died last week.
Caller: is that Mrs. Stott?
Me: no. I've just told you. She died last week. She's dead. I'm her sister.
Caller: oh. Well. If you're her sister, can I speak to you?
Me (incensed): but I'm grieving! My sister has just died! You're being very insensitive!
Etc.etc. I was quite upset. This has never happened before. They usually ring off, and, on a good day, I get condolences, too.
I'll have to think of something else for next time (though - some weeks ago - telling the ambulance chaser that I'd lost both legs was quite fun).