You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I assist you?

USER: I am Christopher Hernandez. I would like change my existing reservation, due to my get together has been postponed.

ASSISTANT: Ok, please wait a moment I'll check your details and revert you.

USER: Ok.

ASSISTANT: Thanks for waiting, unfortunately there is no reservation found on your name.

USER: Thank you for your response.

ASSISTANT: Thank you for connecting with us. Have a nice day!.