To upgrade your seat on a Delta flight, log into “My Trips” on Delta’s website or app to check for available Comfort+, First Class, or Delta One upgrades. SkyMiles members can use miles or bid for upgrades. Upgrades may also be offered at check-in or the gate, depending on availability. Medallion status boosts your priority. For help with the process or to explore costs and options, contact Delta’s customer service team at 877-297-0699 for guidance.