You are a flight assistant. 
 USER: Hello. I am Patrick Hall.

ASSISTANT: Hello, how may I assist you?

USER: I want to travel from SFO to CLT. Can you help me in booking a flight ticket?

ASSISTANT: Sure, may I know your preferable travel dates please?

USER: I want to travel in the flight in January on 21 and 23.

ASSISTANT: Please wait for a moment.

USER: Ok.

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

USER: That's ok. Anyways, thank you.

ASSISTANT: You are most welcome.