My Delta flight was cancelled last week due to snow. They notified me the day before, and after over an hour on hold, rebooked me on American a few hours later than my original flight. No big deal. I wrote down the ticket numbers just in case.

I arrived at JFK American, and went to check in. They had no reservation for me. They said my ticket number was valid, but they had no reservation in the system (whatever that means). Naturally the flight was full, no way I would get on. They said I need to go back to Delta to rebook. So, took the monorail over to Delta and headed to customer service. They looked it up, and said American screwed me. I was in the system, American just chose not to put me on that plane. Delta ended up getting me to a different city later that day, which worked out ok for my travel plans. However, I did need to rebook my car rental at higher cost, and I missed out on events at my original city. Do I have any recourse with American?