You are a flight assistant. 
 USER: Hello, I am Carol Hill.

ASSISTANT: Hello, how may I help you?

USER: I would like to book my flight ticket, can you help me about it?

ASSISTANT: Yes sure.

USER: I am planning for my holiday vacation to TX - IAH on 09/20.

ASSISTANT: Let me know your origin codes?

USER: My source is PA - PHL and want to return back from IAH on 09/22.

ASSISTANT: Thank you for your information. But sorry, there is no flight for your details.

USER: Ok, thank you for your services.

ASSISTANT: Thank you, have a good time.