I absolutely believe you. For many agents, though, the default answer seems to be 'no.' I talked to the two front-facing desks that should have the most familiarity with same day changes (priority check-in, and ticketing). I don't have access to Concierge service so I really didn't have other options.

What's more, I used the 'correct' terminology re: same day changes, and was patient yet strongly insistent. And it was still a total pain.

I imagine most people would've given up long before I did.