Hi again, Robo,
I spoke to yet another Guest Relations CM--this one at DAK. After pleading my case--and, I guess, wrongly telling them that I bought the ticket from a ticket broker--I was told that in fact the value of my ticket was $454.55, not either the amount I paid for it ($465.95) or the list price ($516.53) and that that amount was what they base the upgraded price on. And therefore, I was charged the correct amount.
The CM was not very nice about this at all, especially after she had to go into the "back" in order to verify that what she originally told me--to wit, that their system is infallible--was true. And also I should never have mentioned that I had gotten my information from the Internet, because, apparently, that's just the utterly wrong thing to say.
But it wouldn't've mattered what I said. They are right, they stand by that rightness, and my ticket was worth $454.55 and the upgrade was the $449.64 I paid them. Period.
So either they're wrong but unwilling to do anything about it or the info here on the DIS is wrong, perhaps because WDW changed their policy in the last few days.
Incidentally, while I was standing and waiting for the CM to emerge from the back, I noticed several other transactions that guests were having with CMs at Guest Relations at DAK, and there were a lot of very unhappy guests and quite stern CMs. Perhaps it was just the time of day, but that was hardly the Disney experience I'm used to.
I'm not happy about eating the $61.98, but I'm going to have to. Tomorrow is our last day and I'm not going to spend another 1/2 hour standing in line to find out that the WDW computer is infallible and that I'm owed nothing. If there's any other recourse I might have, please let me know. But right now I'm just writing it off.
ETA: I was also told that the price I paid the ticket broker was more than the WDW value of the ticket at the time it was issued. Which made zero sense to me.