I have had seven phone calls to date from someone claiming to be from Virgin Media (sounded like Indian call centre) who said that VM needed to boost my broadband/internet speed.
I went along with it for a while to see what they would do.
They asked me to go to my pc/laptop and hit windows-R key and enter eventvwr. This pops up the eventviewer which immediately started alarm bells ringing in my head. They use the eventviewer to show error messages and warnings which, though genuine, are completely harmless. But they use these to try to convince you that there is a problem with your computer/internet.
They then require you to download a program call litemanager which allows them to log into your computer remotely.
From there they can search for any private data - bank details, etc. or install ransomware for which they will ask £100s to unlock.
You have been warned!
P.S. they are currently phoning me twice a day - even if tell them I don't have virgin media or I don't have a computer.
Best thing to do is just hang up - and tell everyone in your household to do the same.