You can try calling CO and asking to buy a higher fare if you can upgrade (I don't think there's much of a point of spending more $ for the same Y seat). Some angents may let you do it - others will want a $100 change fee (yeah I know... paying a fee to give CO more $$$ ) As always, if you do find space and the agent will not budge on the $100 fee, hang up and call back. Best of luck! ^