I had a call the other day claiming that my Amazon Prime account was up for renewal and that they had charged me £79.99, all very believable. Other than it was on my work landline which I've never linked to Amazon.
That and I wouldn't trust it anyway.
I've had several of those in the last few days, to my home landline and sounding much more plausible than the run-of-the-mill scam calls. Luckily I'm not a Prime member in any case. so it was easy to tell these were criminals. More seriously, unless for some reason one has cause to be very suspicious of all unexpected calls, how is one expected to be able to distinguish a call like these from genuine communications from Amazon? If you go and hunt around on their web-site, you'll find that they say they won't be communicating by direct phone call, but what if you haven't seen that? (And the Telephone Preference Service is utterly useless as a defence against scammers, so registering with that is no real help to anyone. Equally, having an ex-directory number doesn't seem to help either.)