You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: I have made a mistake while booking a ticket so, I want change my reservation.Can you help me?

ASSISTANT: Sure, may I know your good name please?

USER: My name is Joseph Baker.

ASSISTANT: Please wait for a moment, let me check it and revert back you.

USER: Ok.

ASSISTANT: Sorry, there is no previous reservation found on your name to change.

USER: No problem.

ASSISTANT: Thank you for approaching us. Have a great day.

USER: Thank you for checking.