When are you allowed to bid for an upgrade? Just booked a Premium Econ RT through United and a portion of our return leg is via OS (VIE to ORD) in June. I have the OS confirmation code and went to Austrians site and put in the info under My Bookings but there was no selection option to bid for an upgrade. Is bidding only available when booking with OS directly? I see the option to select seats for $50, but after clicking it, it came back as not eligible.