You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you today?

USER: I would like to change my existing reservation as my plan to go for a holiday trip got postponed.

ASSISTANT: Sure, can I have your name please?

USER: Sure, I am Christine Miller.

ASSISTANT: Ok, please hold on a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no active reservation on your given name.

USER: Not a problem. Thank you.

ASSISTANT: Thank you for opting us.