You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Can you please help me to change an existing reservation as I need to update my trip dates due to my leaves are not approved?

ASSISTANT: Sure, We are here to assist you. May I know your name?

USER: I made a reservation by this name Daniel Perez.

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: That's ok, thank you for your information.

ASSISTANT: Thank you for picking us.