You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Sure, We re here to help you. May I know your name?

USER: I am Dorothy Hernandez.

ASSISTANT: Give me a minute.

USER: Ok.

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: It's ok, thank you.

ASSISTANT: Thank you for reaching us.