You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Samantha Lee here.

ASSISTANT: How can I help you?

USER: I want to reserve my ticket from DCA to SEA, can you please help me to book a ticket?

ASSISTANT: Your travelling dates please.

USER: Sure, my planned dates of journey are from 05/12 to 05/14. Please make sure that the price limit is 500.

ASSISTANT: I am  sorry no flights found on your dates. Thank you.

USER: Ok, no problem. Anyways, thank you for your service.