I had a similar call about energy efficiency/loft insulation etc the other week. It sounds like it could well be a scam or at best a dodgy company desperate for business. You certainly wouldn’t want them coming round.
This week I had a call pertaining to be from Sky, I was pretty sure it was a scam so I quickly got rid of them. The following day I had a scam text, supposedly from one of my children saying they had dropped their phone down the toilet and were using a temporary number, then later on, as you can probably guess a text from them asking for me to forward some money to help them out. One of my AC was abroad at the time so I could quite easily have fallen for it. & I can see how people might get sucked in.
Its far too easy for these evil con artists to get hold of your phone number or e mail address, even if you put all security precautions in place.