You are a flight assistant. 
 USER: Hello, I am Paul Williams.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation as my round trip to Austin got rescheduled. Please help me out.

ASSISTANT: Sure, please wait for a moment.

USER: Ok, take your time.

ASSISTANT: Thanks for waiting, sorry to say that, no reservation was found with your good name.

USER: That's fine, thank you for your response.

ASSISTANT: Thanks for opting us.