You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am planning to book a ticket form PHL to CLT. Can you please help me out?

ASSISTANT: Sure, may I know your trip dates?

USER: I am planning to travel on Dec 12 and return back on Dec 14.

ASSISTANT: Do you have any other requirements?

USER: I am looking for a normal cost airline.

ASSISTANT: Can I know your name please?

USER: My name is Nicholas Allen.

ASSISTANT: Ok, please wait for a while.

USER: My return time should be evening.

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

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

ASSISTANT: Most welcome.