We've actually paid for a subscription (£40pa) to the Caller Preference Service and we get very few cold calls these days. If we do, we report the number to the CPS and they contact the companies for us, and can prosecute for nuisance calling if it persists.
The people who are calling you, Captain, won't mind if you are TPS registered, if it's from overseas they can still get through. It's the TPS you should complain to. Dial 1471 after each nuisance call, to get the caller number, if they've not blocked it.