You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you today?

USER: I am planning to change an existing reservation, due to health issue. Can you please help me out?

ASSISTANT: Surely, I will help you out. May I know your name please?

USER: My name is Richard Clark.

ASSISTANT: Thanks for your name, please wait.

USER: Sure.

ASSISTANT: Thank you for waiting, no reservation was found on your name to change.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you for choosing us.