You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I provide assistance to you?

USER: I want to change an existing reservation due to my adventurous trip got postponed.

ASSISTANT: Ok, may I know your name?

USER: I am Justin Evans.

ASSISTANT: Please wait a moment I will check and get back to you.

USER: Ok.

ASSISTANT: Sorry to say, no reservation found with your name.

USER: Ok. Thank you for your help.

ASSISTANT: Thanks for opting us, have a good day.