You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What can I do for you?

USER: I have a sudden meeting to attend, I would like to change my existing reservation.

ASSISTANT: Sure, I will help you. May I know your name for checking previous reservation?

USER: My name is Thomas Mitchell.

ASSISTANT: Ok, please wait a moment, I will inform.

USER: Sure.

ASSISTANT: No reservation found on your name Thomas Mitchell.

USER: Thank you for your help.

ASSISTANT: Do you want to know anything else from us?

USER: No, thank you.

ASSISTANT: Thank you for reaching us. Have a nice day.