You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I want to change my existing due to postpone of my event. Could you please help me?

ASSISTANT: Sure, I will assist you with that. Can you please mention your name for further process?

USER: I am Karen Walker.

ASSISTANT: Ok, please hold on a moment.

USER: Sure.

ASSISTANT: There is no previous reservation available under your name.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for reaching us.