Originally Posted by
MeltingAlf
I believe A3 moves people from Y to J as an operational upgrade when they're fully booked/overbooked and yet have empty spaces in J - I've seen this happen on ATH-LCA before. So if in OP's case he/she was indeed (as by the A3 rep) upgraded at the last time, but as an op-up and not via upgrade vouchers. I think the rep didn't say that part out loud because something definitely screwed up somewhere.
I kind of indirectly said the same thing, which still begs the question: "why would there be any problem with their reservations, if no upgrade per voucher was involved at all?" (perhaps indeed the fact, that they failed to check-in before - presumably - everyone else, did have something to do with their issues?)