Are you ex-directory? We're not on the public electoral register either.
Hi there is True Call but the reviews online say that CPR call blocker is efficient and much better value
http://www.cprcallblocker.com
http://www.amazon.co.uk/CPR-Capacity-Nuisance-Call-Blocker/dp/B004BTVQ5E
http://blogs.which.co.uk/technology/phones-3/cpr-call-blocker-vs-truecall-call-blocker/
good luck
"...possibly along with other calls that are probably 'innocent', maybe important."
This can be a major problem when 'withheld' calls are blocked, you can't selectively block 'withheld' as they do not present a unique caller ID.
Most of the NHS, LA, Gov,.... present as 'withheld'. Some blocking systems ask the caller to release the CLID by using the 1470 prefix, some ask the caller to release the CLID leaving it up to the caller to decide how to do it, others just say 'sorry this person does not accept anonymous calls', in the last case you rely entirely on the caller having been trained what to do.
if you want a bit of fun just answer them ask a lot of your own questions get really personal with the questions and swear at them be realy abusive let’s face if there scammers what does it matter
I try to be polite - as long as they are polite to me and take 'no' for an answer. If they try to tell me that I am stupid, don't understand what I am saying or what I might have done, I get a little less polite. Also exempt are people who are setting out, blatantly, to con me - my response to them varies from day to day.