If this happens again, get the name of the company he represents. Then look up the company. When my father went into a nursing home, we found amongst his papers some letters about several kinds of shares, saying he should sell them for such-and-such amounts of money. We thought they were scams, but they turned out to be genuine, since the companies concerned had been merged or taken over or amalgamated ( or something) . Because there had been a delay ( father had lost his grip on his affairs ) we paid some small penalty, but there were some thousands of pounds in it for his (eventual ) estate.