Understand the OP's frustration, but as others have noted (maybe a bit harshly), it's clear about the expiration. Whether one is too busy is not UA's concern.
That said, I did get an extension on an expiring $350 by contacting Customer Service and asking nicely (this is about a year ago).
Good luck next time and try to get an extension, use CC, or gift to a friend... they'll certainly appreciate it.