You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you today?

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

ASSISTANT: Sure, can I know your good name?

USER: Sure, my name is Donald Allen.

ASSISTANT: Please hold a moment.

USER: Sure.

ASSISTANT: Thank you for waiting, there is no recent reservation found with given name.

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

ASSISTANT: Thank you for contacting us.