Hi Tetiana. A similar thing happened to me today. I booked with a Spanish teacher. Fifteen minutes before the lesson, he contacted me, said he had an emergency and asked if we could cancel and rearrange. Of course, I agreed after the lesson time. I went through the Itaki procedure and received a credit back. I had fully intended to re-book with the teacher and discovered he had blocked me that day.
I thought it was rude, childish, and unprofessional. If he didn't want to work with me, he could have just said so. Thankfully, there are other great teachers out there.