+1-844-414-9223 If you want to upgrade your seat on a Southwest flight and you can't find any options that work, go to Air1Network. They have a blog titled "How can I Upgrade to Business Class Free on Southwest," where you can quickly and simply upgrade your flight seat. Call Southwest's customer support line, which is available twenty-four hours a day, seven days a week, at 1-844-414-9223 for more information.