Do you want to upgrade your seat to first class or a big window seat for free? You're in luck, as the Delta seat upgrade policy lets you upgrade a seat for free. Sign up for the SkyMiles program and earn miles by traveling or utilizing other Delta services like car rentals, shopping online, etc. Also, you can upgrade your seat by booking a flight with a Delta credit card. For further information, contact Delta Airlines customer service or visit the website. Also, you can call +1-800-865-1848 to talk with travel experts and get your doubts answered.