You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you today?

USER: I want to change my existing reservation due to my health issues, can you please help me with this?

ASSISTANT: Sure, may I know your name for the changing process?

USER: My name is Amy Lewis.

ASSISTANT: Thank you, please wait for a while.

USER: Sure.

ASSISTANT: Sorry, we couldn't find a reservation on your name to change.

USER: Not a problem, thank you for checking.