Those phone calls from "a local energy advisor" aren't real people ringing you but are a series of recordings which are done in such a way that you think they are real, In reality, they are just cold callers trying to get you to agree to a survey on your house to panic you into spending lots of money.
Here's a youtube clip of what happens when "Chris" rings someone who is playing a trick on "Chris" by using a series of recorded replies himself
https://www.youtube.com/watch?v=kRimYymMVus