I just called the Jessops shop in Ealing 3 times. The first two times, it was engaged. The last one, nobody ever answered, although I let it ring a long time. If they had answered and had had what I was looking for in stock, I would have gone there immediately and bought it without any question. That's a missed sale worth about £800. Nevermind, I'm happy to give my money to someone else.
Note for people who are not French: the title is part of the lyrics from a song by Jacques Dutronc about a phone that always rings and that nobody ever answers.