This happened to me once. I exchanged Several messages with the teacher before the class and I was the first student for him after an absence, so I actually can’t imagine that he totally forgot about the class. When he didn’t show up for class, I sent him several messages via italki and Skype during class time and afterwards. A couple of days later, I checked the “There was a problem” box. The teacher never came back to me to explain himself and he also didn’t reply to the italki team. I got my money refunded.