You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I aid you today?

USER: I want to change my reservation due to health problem, can you help me?

ASSISTANT: Sure, I am glad to help you with that. Can I know your name to check your previous reservation?

USER: Myself Christine Williams.

ASSISTANT: Please wait a moment to check.

USER: Sure.

ASSISTANT: We regret to inform you that there is no reservation found on your name in our database.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for reaching us, have a great day.