You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, what can I do for you?

USER: Myself Donald Moore. My holiday trip has been postponed, so I would like to change my existing reservation. Can you help me?

ASSISTANT: Sure, please wait for a minute. Sorry, there is no previous reservation found on your name to change.

USER: No issue. Thank you.

ASSISTANT: Thank you for contacting us.