Originally Posted by PBAudit

For future reference, another option to paying the additional $550 to change the ticket, is to plan a SDC ($50 for General Member) to the earlier flight. Unlike Delta's SDC policy, even with the recent enhancements, United's SDC policy is much more generous. Your friend may have moved up to an earlier flight beginning 24 hours from the original departure date/time. Thus, if the original flight was leaving at 5 pm on 6/17, she could try to confirm an earlier flight starting at 5 pm on 6/16 (i.e. any flight leaving 5:01 pm on the 16th).