I read here that some folks have managed to convince CO elite phone agents to transfer them to the UA elite desk. How do you do this?

My reservation: CO codeshare operated by GoJet / United Express, 3 passengers (2 CO Platinums, 1 baby without status).

Any attempt to assign or change seats on ual.com produces "There was an error updating your PNR."

First call to CO: "Sir, I don't have any ability to assign seats or transfer you to United. You'll have to use their website or call the 800 number". "But..." "SIR!!! You'll have to use their website or 800 number!!!"

Second call to CO: "I don't know anything about United's elite desk and I cannot transfer you, but let me call them." After a 10-minute hold: "They only have seats in Economy Plus and you'll have to pay for those."

Third try: Refuses to transfer me, calls herself, after a long hold comes back with B,C,D seats in Economy Plus. Hallelujah! No "upgrade: pending," but fine, with only 6 seats in F this woulda been a long shot, anyway.

So, how do you convince a CO phone agent to let you talk to someone at United?