I don't know if this idea might have any mileage, but....
Some of these callers leave a genuine number on caller ID. If they do, I always ring them back on the chance it might have been a genuine call from someone I might have needed to speak to anyway.
If it proves to be one of 'those' calls I always have something nasty to say to them, some don't answer and leave you listening to music. The point is, ringing them back I assume blocks lines up?
Might it be worth someone setting up a web site with these numbers and then we ring them, keep on ringing and block their lines as they do to us?
The telecom industry has done nothing, the UK government seems tooth-less to do anything, but the technology is there and able to do something given enough wish to do something about it.