Take it from someone who works in the industry. Telephone Preference Service is your friend
Take it from someone with a phone. Telephone Preference Service isn’t good enough.
The vast majority of cold calls I get, and I get a lot, have a number of common denominators: The line quality is terrible; it takes several seconds before someone appears on the line; they have thick impenetrable accents usually of the Indian Subcontinent variety; and with a voice straight out of Mind Your Language they’ll tell you that their name is “Kevin” or “Sally”.
They then ask for Mr Jones. Mr Jones is my Grandad, or was, he died about 25 years ago.
You mention the TPS and they laugh in your face; the TPS is powerless for calls originating from overseas, and they know it. They’re often rude as soon as they realise they’re not going to get a sale, they deal in volume in the same way that spam does so they don’t give a tuppenny toss about any threats, requests or pleas you make.
The most effective way I’ve found of dealing with them is to go, in a sad voice, “I’m afraid Mr Jones is deceased.” Some, rarely, will have the grace to sound apologetic; most just hang up immediately; sometimes, they don’t know what ‘deceased’ means; and in one case recently, she told me that it’s “not possible” and called me a liar.