You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Can you aid me to book a flight ticket from JFK to OAK?

ASSISTANT: Sure, may I know your trip dates please?

USER: My trip dates are Aug 26 and Aug 28 respectively.

ASSISTANT: Do you have any other requirements?

USER: My return time should be in the morning.

ASSISTANT: Can I know your name?

USER: Sandra Walker here.

ASSISTANT: Sorry, we regret to inform you that there is no flight available as per your request.

USER: Thank you for the help.

ASSISTANT: Most welcome.