Originally Posted by
gateH15
or if OP has status or AC membership I would try to go there and let agents in FL or AC to help you with seats or upgrade.
I would not wait until you get to the airport since that flight leaves late on Thursday night, after all other options have gone. There are flights to BCN from JFK, PHL and CLT but they all require you to leave ORD Thursday morning or early afternoon. This isn't about calling to get your pre-assigned seats back, but getting a commitment that you will fly in your booked cabin (not sure you can get a solid commitment, but you can ask them to document it in the record) - there's nothing to lose from asking.
If you can't leave earlier on Thursday then you should probably be prepared to take a downgrade to Y, or fly on Friday (but Friday there is even less space than Thursday it seems).