We've also been bothered again in the last week or two after some blessed time without getting calls. I was very taken aback last week when asked to answer survey questions (oh really?). I politely told the gent that I never answered questions via telephone and thanked him for his call (after all, they are only trying to earn a living), to be told very firmly that I could expect to get further calls from him, Madam, indeed to expect to hear from him again 
Yes, he did ring again and again twice the next day, but after OH answered with a loud bell, the calls ceased. I'm not a happy bunny
, mainly because I realise that calls like these could be quite frightening to some as I did feel a little threatened.