You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Cynthia Turner.

ASSISTANT: How can I serve you?

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

ASSISTANT: Sure.

USER: Thank you.

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT:  Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.