You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Cynthia Baker here. I need to change my existing reservation due to my exams, can you help me?

ASSISTANT: Sure, please wait for a moment to check your details.

USER: Sure.

ASSISTANT: I have found your reservation, may I know your new travelling dates?

USER: I am willing to travel on 04/17 to 04/19.

ASSISTANT: Can I have your airport codes?

USER: My airport codes IAD to LGA.

ASSISTANT: Do you have any requirements?

USER: I need a direct flight.

ASSISTANT: Sorry to say, no flight is available for you.

USER: Ok, no issues.

ASSISTANT: Thank you for reaching us.

USER: Thank you for the help.