You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: Please help me to book a flight ticket from SEA to LAS.

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

USER: My travelling dates are from July, 29 to July, 31.

ASSISTANT: Do you have any other requirements?

USER: I prefer single connecting flight and I need an business class to fly.

ASSISTANT: Can I know your name please?

USER: My name is Michael Smith.

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

USER: No problem, thanks for your information.

ASSISTANT: Most welcome.