You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Lisa Phillips.

ASSISTANT: How can I aid you?

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

ASSISTANT: Sure, give me a minute.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found under your name.

USER: That's ok, thank you for your information.