I am posting this for a friend, so I might not have answers to all your questions, but here is what I do have.

IAD-CUN, June 24 - July 4. Return flight changed from 11.55 AM to 7.30 AM. They called AA to change the return to a later flight and was told that there isn't enough time to make the change. As in, because their departure is so soon, AA cannot change the July 4 return.

AA is selling tickets for the 3.3.0 and 4.40 flights on July 4, so I don't understand why my friend cannot be changed to one of those flights.

I have no experience with AA, but did tell them to hang up and call back. Have done so twice with the same answer.

Is this correct? Is this the AA policy?

Thanks for any help.