I regularly block these numbers but they keep trying. My mum has had the broadband one many times and she's never had the internet. Luckily she can recognise these types of calls as scams but there are plenty of elderly that don't.

If you want to see how these scams operate then I recommend you check out Jim Browning https://www.youtube.com/channel/UCBNG0osIBAprVcZZ3ic84vw

Unlike a lot of Youtubers that just take the pi$$ and waste the scammers time,Jim goes into it more deeply,even taking control of their PC's and in some cases getting refunds for the victims.