OP here with an update.
I had my massage. I was anxious, not wringing hands anxious, but still mentally prepared to shut down a ton of sales tactics. I was thinking of ways to preemptively tell the massage therapist to not use marketing techniques.
When I spoke to my DH about how I called to book the massage and how the owner of the place was really pushy, DH said that he expressly told the lady at the desk when he bought the gift certificates that I didn't want any pushy sales tactics.
I got to my appointment and was waiting in the lobby. Several people came out after their massages and paid. I overheard one of the ladies at the front desk launch into what probably was supposed to turn into a pushy sales technique. She asked one of them "Do you know about our wellness program?" He slumped his shoulders in exasperation and let out a huge frustrated sigh and said "yesss" in an angry tone. That shut her down and she didn't continue.
I figured that was a good way to shut that down but I didn't think I had it in me to produce such a frustrated sigh. But I was prepared to just say "yes" when she asked if I were familiar with the wellness program.
Luckily, the massage therapist was wonderful. I had a relaxing massage. He wasn't pushy at all.
When it was over and I went to the front desk to produce my gift certificate and the lady asked if I were familiar with the wellness program, I just said "yes." And as she inhaled and seemed like she were going to continue, I added "luckily, I have gift cards!" So she stopped trying to sell me things. I'll use that tactic next time too, even though it will be my last gift card.