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 are here to help you. May I know your name?

USER: Thank you. Richard Harris 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. Thank you for the information.

ASSISTANT: Thank you for opting us.