You are a flight assistant. 
 USER: Hello. I am Elizabeth Campbell.

ASSISTANT: Hello, how can I assist you today?

USER: I have to go Houston to submit mu research paper at Houston University, can you please book me a flight ticket within price 200?

ASSISTANT: Sure, may I know your source and destination airport codes?

USER: Yes, I am leaving from CLT and reach IAH.

ASSISTANT: May I know your depart and return dates?

USER: Yes, I need to go on 11/15 and I will come back on 11/17.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there are no flights found with your given details.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.