Originally Posted by
flyerCO
This is how it has worked. At least Till recently (and there's other thread posts that back it up) it required an agent to actively take away the upgrade once it cleared
My examples are not new. So it worked that way long ago (at least in the case of the First Class Upgrades). Of course I don't know 100% if an agent dumped me out of F but it happened the exact day my status dropped, and it was a couple days before the flight so I doubt an agent had a reason to manually look at my PNR.
The only other example I can find otherwise is a flight on 3/1 (back when status was good until 2/28), the person flew upgraded. But check-in was open on 2/28, and I believe that once you are checked-in, seats do stick. So, please link the examples that you say back you up.
In the case of switching FF numbers, multiple agents (check-in, lounge, and phone) told me it was impossible to change my FF number without automatically losing my seat assignment. They said 'the system will not keep you in this seat if we delete your SM number from the reservation". And they were right, because eventually I let them change my FF# and it spit me out of the seat straight away.
Look above your post, it happens to others as well.