I told the therapist I would update my review, so here it is. Later than I originally said, but here nonetheless.
1) I did end up getting a credit from Groupon. Used the credit to buy a massage from a different provider, but I probably won't use Groupon again unless it's for known stores I already frequent.
2) The therapist called, left a voice message, then sent a bunch of text messages a few days after my original review. I presume she did this after she saw my 1-star Yelp review. She was trying to get me to change my review. I now understand what Anne T. meant by harassment. She kept calling my review "malicious" and "evil", then trying to get me to reschedule a free massage. Umm... no thanks. I'm getting all sorts of crazy vibes, and I don't believe in getting services like this for free. She kept blaming the owner of the salon repeatedly because they were waxing the spa floor (apparently without giving any notice to any of the therapists at the salon). Even if it were true, it is still her responsibility for letting her clients know when she needs to reschedule, regardless of the reason why a reschedule is needed.