You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Can I know your name please?

USER: My name is Christopher Thomas.

ASSISTANT: Please wait.

USER: Sure.

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

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you for the information.