You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am David Harris. While checking my recent reservation status I mistakenly cancelled my reservation and again I need booking to PHL from AUS, could you mind help me in booking?

ASSISTANT: On which dates you are willing to travel?

USER: I want to travel on 03/31 and want to return on 04/02.

ASSISTANT: There is no flights available.

USER: It's ok, thank you for your help.

ASSISTANT: Welcome.