You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am Kathleen Garcia. I want to change my existing reservation because my trip dates are postponed, can you help me?

ASSISTANT: Please wait a while.

USER: Sure, take your own time.

ASSISTANT: Sorry to say, there is no reservation on your name in our database.

USER: It's ok, thank you for checking.

ASSISTANT: Thank you for opting us.