Thanks for letting us know. It looks to me like a teacher might have had an emergency and had to cancel extremely short notice (there have been some backouts in China recently, but not sure if that was the issue).
Please email [email protected] with that screenshot and we will sort this out tomorrow.
You will of course get your credits back.
Very sorry about this, it is extremely rare that this happens and we will check what happened to the teacher. I hope it was nothing worse than a blackout