My usual way of dealing with people like this - but only if it is something I'm possibly interested in, such as cheaper energy - is to say, "I can't right now but do you have anything you can leave me to read so I can do some research and make some comparisons?"

Actually, I just said 'No thanks' when ADT came round so I don't know what their response would be. But back in the day the energy reps were all unable to leave any details about their prices or tariffs. It had to be discussed then and there or else I would miss out on the opportunity to save £££. Funny, that...

Obviously it sounds like everyone on SE23.com is capable of looking after themselves, but it's the naïve folks who are more easily intimidated that I worry about most. They could end up being talked into buying an over-specced, over-priced system.