You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Due to inconvenience of my work, I want to change my reservation. Can you please help me for that?

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

USER: My name is Joseph King.

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: Anyway, thanks for the information.

ASSISTANT: Thank you for reaching us.