Originally Posted by
golfingboy
There is only one U. The different in "U"s you are seeing is for different upgrade avenues [MVP via Y/YAS fares, Golds via H+, Mileage, and Guest Upgrade], but they all book into the same U bucket. If U is not available for Guest Upgrade Certificates, then the Gold U or the Teal U will not be available as well. So, if a Gold sees the Gold U then an MVP will see a teal U, both of them can confirm the upgrade as early as booking. Since the OP is a Gold, the OP is eligible to upgrade via all avenues granted he meets certain fare class criterias for each upgrade avenue.
Bottom line, if you see the slashed U next to the flight information in the flight search, there is no U available.
So it's sounding more and more like the U wasn't available when he booked. Can the OP clarify?