I don't recall the Hyatt status, but I know I had earned Diamond on my own back in the 90's and maybe still into 2005. I now vaguely recall CO status, but I don't see how that could be mistaken for UA. Not to mention that the fallout from the UA-CO merger can hardly be blamed on Amex. And still there is the Hertz comment that isn't accurate. But like I posted above, I apologize if I got it wrong.
As for the other comments about booking errors, I have not seen that at all. Maybe they are accurate for the poster, but that doesn't mean that all Centurion members are having these problems. I doubt such a thing would be possible. I called Centurion very early this morning (because I'm in Europe) and they answered on the first ring. As they did the week before. Maybe they are having peak call time issues, but a whole lot of businesses in the US and around the world are having staffing problems. I would not single out Amex in such a case and I would not expect it to continue forever. And in my case the last two calls I made, which were around flight re-bookings, were very professionally handled. I was actually kind of surprised to get such a good agent at that hour.