You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: I need your help in changing my recent reservation.

ASSISTANT: Sure, may I know your name?

USER: My name is Ronald Martin.

ASSISTANT: We found your reservation, can you share your journey dates?

USER: March 23 and 25 are my in and out journey dates.

ASSISTANT: May I know your airport codes?

USER: HOU and IAD are the respective in and out airport codes.

ASSISTANT: Do you have any preferences?

USER: I need a direct flight.

ASSISTANT: Give me a minute.

USER: Sure.

ASSISTANT: Sorry, there is no direct flight on your given dates.

USER: That's ok. Thank you.

ASSISTANT: Thank you for opting us.