I got a bunch of these calls in my voicemail lately, and then I finally got one I was able to pick up. I waited for a person and said "your message said my warranty will expire, please sign me up for my warranty extension, I'm ready to go ahead with this". The lady confirmed my phone number and then said "sorry for the inconvenience sir, please disregard this call" and hung up; I haven't gotten a call since. I guess she was really skilled at identifying time-wasting assholes just by tone of voice.