You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I aid you?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, We are here to help you.

USER: Thank you.

ASSISTANT: May I know your name?

USER: Elizabeth Lee here.

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: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.