If you've never received these calls you are very lucky. There is now a new variation on the theme from two different supposed sources.
Last Friday I was called by someone from "Microsoft Technical Centre" advising my computer was under attack. Instead of telling me which buttons to press, he wanted to give me the contact details for "Microsoft Service Centre in London" who would be able to sort the problem out. He wouldn't shut up and started shouting at me when I told him he was a crook. Last number barring was put to good use.
It appears that TalkTalk customers have been contacted by scammers allegedly from TT, who are also advising to contact a different TT department. The calls originate in India and the call centre scripts have been given to the UK media by the whistle-blowers.
Finally, if you think the days of the letter scam have gone since the advent of e-mail, sorry to disappoint. My aunt recently received a letter from someone working for a Hong Kong bank, offering her a share of a deceased person's wealth before the government got their hands on it.