You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: I'm Mark Turner. Can you please do me a favour by booking a ticket from IAH to DEN?

ASSISTANT: Can I know your travel dates?

USER: My travel dates are 12/30 and 01/01.

ASSISTANT: Please give me a minute.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no flights available on your requested dates.

USER: That's ok, thank you for your service.

ASSISTANT: You are welcome.