I feel sorry for the OP who appears to be wasting his time with UA and not directing his energy at the source: the travel agent (and his company's policies). Shocking that a travel agent would tell its principal to correct the former's mistakes when that is his/her job.

While reading (parts of) this thread, I had the same thought: with 5h, buy a walk-up ticket OAL, make the SFO flight, and work to get the bag to the destination. I assume UA would get the bag there even if OP was not on 1st flight (UA) on a separate tix--correct?