When You Change Flights Due to Overbooking, Ask for an Upgrade
First class flights are usually insanely expensive, but there are some tips and tricks for getting cheap (or better yet, free) upgrades. If your flight is booked and you choose, for example, another flight, you can also try to negotiate an upgrade.
Gilbert Ott of travel site God Save the Points tells Business Insider that flexible travelers can often use their flexibility as leverage to negotiate an upgrade to First or Business Class:
If the flight is oversold, [the airline] usually asks for volunteers to board the next flight … I get more money than I actually paid for the ticket, and quite often I also get an upgrade. ..This is your best option if you don’t have miles or airline status.
This actually happened to me recently. I asked for an earlier flight and since more seats were already booked on my original flight, the boarding agent said he would give me a better seat. It wasn’t a major upgrade, but I had more legroom and didn’t even have to negotiate. The next time you’re on a packaged flight, it’s at least worth asking if you have the option of choosing a different flight.
Most Effective Way to Get Free Upgrades for General Travelers | Business Insider