You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: Can you please reserve me a flight ticket from PHX to AUS?

ASSISTANT: Ok, may I know your travelling dates please?

USER: My travelling dates are May 14 and May 16.

ASSISTANT: Is there any specific class preference for you?

USER: I want to travel in economy class.

ASSISTANT: Do you have any other specifications please?

USER: My return time is afternoon.

ASSISTANT: May I know your name please?

USER: I am Christopher Martin.

ASSISTANT: Sorry to inform you that, there is no flight found as per your travelling details.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for opting us.