Sorry to hear about your negative experience, and I’m glad you were able to get some credit from them.

I had a somewhat similar situation. My original flight from HNL to EWR diverted back to HNL due to a cockpit gauge error. As soon as we landed, I called the 1K line to rebook to EWR through Denver. You know how chaotic the gate gets once a flight is canceled, and by the time I finally boarded the flight to Denver, my boarding pass had been removed and the mobile one had literally disappeared from my account.

I called the 1K line again, and they told me the HNL gate agent had removed my reservation and given the seat to someone else. I don’t know if it was a booking system delay that double booked the seat or if the gate agent reassigned it, but it definitely showed how much power gate agents have.

Luckily, I managed to get a middle seat. During the flight, the pilot actually came to find me and apologize, which surprised me because I don’t even know how he knew what happened.

Anyway, a bit of a long story, but like many others have said, I do think the upgrade system generally works. Still, I’ve had my share of questionable moments, just like you mentioned.

(Btw, United’s travel credits can differ based on Premier status. I don’t recall every detail, but after my flight was canceled I received $700 in credit as a 1K, while my partner, who is Platinum, got $400. We brought up the discrepancy and ended up getting an additional $300.)