You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Christine Hill here. I need to change my recent reservation because my trip dates are postponed.

ASSISTANT: Ok, wait a moment I will be back with the proper information.

USER: Sure, take your own time.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to change further.

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

ASSISTANT: Thanks for choosing us.