Last week end a couple (adults) came to my place for a private tuition. At the end I told them that if they were happy with me and the books which I suggested, I would ask them to confirm if they would come back for their second tuition and also if they bought the books or not, because my planning depends on it (I said it a few times). They didn't contact me anymore, so I decided they didn't like me, but this morning they came for a tuition. My boyfriend opened the door and told them: "She didn't expect you as she was waiting for you to confirm about today, but please come in, she will see you in a few minutes". The couple left. The thing is it would be a very convenient lesson for me and I would like to keep it. What should I write to them, how to explain the situation? (I don't have their mobile numbers).