This is my 2nd time flying Alaska (first time being maybe 10 years ago), so I was not aware how terrible AS' IT system is. I booked an AS flight that was sold as a AA codeshare, since I fly AA most of the time. I had intended to buy a seat upgrade for Premium Class. The Alaska Air app shows PC seats available, and lets me pick one and proceed all the way through payment screen. But when I try to make a payment, it fails with some generic error message. I'm also able to pull up the reservation on AS' website, which shows all PC seats as greyed out. I called AS customer service, and they basically told me "as a for-profit business, we would love to take your money, but our IT system sucks. So you can only buy seat upgrades if you booked the flight as an AS flight." I was flabbergasted at how bad AS's IT system is. My question is: is there another way I can purchase a seat upgrade? Can I do it at the airport at AS' counter? Or some ther way? I could cancel, but since it's a non-refundable flight, I would only get AA credits, right?