Please let me know if this is posted, I couldn't find it.

I am, for the first time in 25 years of flying UA, on a code share flight on US Airways Metal.

For a while I have been trying to select a seat, even called US Air, and was told I can only sit in the back middle, that the only open aisles are reserved for their elites. I also asked to add my United MP number, and was told its already on my record since its code shared.

I checked in today, and am still in a back middle. I was offered to pay for checking my bags, and my BP says I am to board in Zone 3. I thought Star Gold boarded before Zone 3.

Any ideas on what do do? I feel like I am simply flying on a non Star Alliance carrier for the first time and getting nothing from them.