You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am John Green.

ASSISTANT: How can I aid you today?

USER: I just want to change my existing reservation. Can you help me in this?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please hold on.

USER: Ok.

ASSISTANT: Thanks for being patient, there is no reservation found on your name to change.

USER: Not an issue, thank you.

ASSISTANT: Thank you for approaching us.