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

ASSISTANT: Hello, how may I support you today?

USER: I would like to celebrate the brother's birthday in Philadelphia with my sister. Could you please help me in booking a flight ticket?

ASSISTANT: Sure, please share your travelling dates?

USER: My depart will be on 12/13 and arrival on 12/15.

ASSISTANT: Help me with airport codes?

USER: My source code is WA-SEA and destination code is PA-PHL.

ASSISTANT: Do you have any other specifications?

USER: Yes, I need a halt. I can afford upto 200.

ASSISTANT: Sorry to say that no flights are available with your preferable price.

USER: Ok, no issues. Thank you for your service.

ASSISTANT: Thanks for opting us.