[Dom]

If you booked a US Air flight through United, it is probably a "code share" flight. A code share flight would have different flight numbers for US Air and United, but it would be the same flight. In my experience, you always check in with the airline that is actually flying the plane, and not with the airline that sold you the ticket. It look like United gave you bad information. Unfortunately, other than complaining to United, I doubt that US Air will do anything for you.