Part of the problem seems to be allowing yourself to be bumped for a confirmed punt. Did you suggest you'd confirm at 8pm or did she ask you to?
If it was her suggestion then it's her fault, if you suggested it unfortunately you left the door open for someone who could in theory guarantee the punt at that time, still her fault though for accepting.
As reasonable as it sounds, offering to make a confirmation phonecall I found it sometimes leads to this.