Re: Reporting calls
Yep. ICO or even Ofcom. It's a bit of a faff but there's a webform for either that will direct you to the right place. And if you're on TPS you can complain to TPS directly too.
It won't stop those kinds of calls, but it'll limit them somewhat.
Far easier is to just configure your phones better - unless you know the number, have it silently push to a voicemail. If you know the number, have it ring as normal. That's really easy on mobile (and no app required), easy on SIP and available on traditional landlines if you pay (but, to be honest, just get a mobile phone SIM, virtual office or a SIP line and live in the 21st Century a bit).
I'd rather not rely on some third-party to police that for me, to be honest, and just have a system that works for me rather than tries to sell me out and then expects me to pay to keep that away. I've used two mobile SIMs, one for the last 20 years on the cheapest calls package, for years, one kept utterly private, and never bothered with a landline number at all. I get basically no spam. What I do get rings off silently into nothing and doesn't disturb me, while my contacts get straight through to me.
I also have a SIP account with its own number and, hell, even Skype can give you a number for a tiny monthly amount now. They'll never stop all the Indian / Asian / Cayman Islands etc. ones because they are just out of their jurisdiction, so just have your phone send them silently to voicemail or even just to a permanently-ringing extension (which is what my phone does... if you want to hear from me genuinely, you'll realise after the 10th ring and just text me instead).
Don't pay the people creating the problem money, with "Caller ID Blocking" charges, etc. on your BT line. That's just dumb. You're just paying them to solve the problem they created. Just start using a number on your mobile or move to IP phones (so even your house phone can just be a IP extension). I have one SIM for work (10+ years of self-employment, 10+ years of general usage on top), one for personal, neither ring unless it's someone I know and the personal number almost nobody knows. They're even on different networks, so if one stops working, I can just switch to using the other.
And for business, virtual office numbers are dirt-cheap and a real live human answers your calls like a secretary, with your company name, just takes a message, and then sends it to you some other way.