How to Upgrade Seat On Allegiant Air?
+1-844-414-9223 Passengers can select these Allegiant Air upgrades options during the booking process. Or later via the "Manage Travel" section on Allegiant's website or customer service. And please note that seat assignments cannot be changed at the airport or once a boarding pass has been printed. With upgrade options available during booking and after, passengers can easily choose extra comfort for their flight.