Someone from the studio emailed me apologizing for the incident. She assured me that the instructors would be further trained to handle mixed-level classes. She also offered to refund my money and offered a free yoga class for my mom and I. She seemed genuinely upset this had happened. Since I have left the area I have not taken her up on the offer, but I thought it was really nice. I suspect the incident I previously described may have been a fluke, as she seemed to care very much about the safety and well being of SDY clients.