If they opened the front door and stepped in, calling out "I've come to sell you a funeral plan/fix the non-existent fault on your computer/tell you about a scheme for the government to pay us to install a new boiler if you jump through the right hoops" we would tell them to get out right now and not come back. We should not accept the invasion of our telephone either.
It is quite irrelevant that they are trying to earn a living, it is an aggressive way of getting us to buy their product or use their services. The individual caller is not to blame (unless they get abusive) It is the owners of the business that they are representing.
I believe that they can be prosecuted if they ignore a direct instruction to stop calliong you, so the way to get rid of them (well, from that firm anyway - there will be more) is to say politely but firmly "No, I do not want xxxx and do not call me again. Please remove my name from your calling list and make sure that I do not hear from your firm again. And what was the firm's name again? How can I get in touch with them?" That at the very least puts the wind up them.
They are legally obliged to tell you the name of the firm they are calling for, and their own name, so that the call can be identified. If they don't/won't they have something to hide. If you can be bothered, make a note of the caller's name, the firm's name and contact details, and the date and time.
Daughter not allowed to know new baby’s name until she visits him
don't have a problem with under 16's having free bus travel,BUT

It depends on my mood I'll either say "No thanks" and hang up or I'll string them along a bit.
