Hold them on the phone as long as possible.
As someone in semi-retirement I used to walk them down the garden path and throw them in th compost heap. Alas the PC I was pointing them at (w98) died and I cant be arsed to find the disc to set up a VM. I've have been tempted to brake the law and take them over but can imagine how pissed off you'd be going up before the beak for doing the world a favour.