You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Elizabeth Green.

ASSISTANT: How can I help you?

USER: Can you help me to change my reservation?

ASSISTANT: Sure, please wait a while, let me check.

USER: Sure.

ASSISTANT: There is a reservation on your name, please share your new travel details.

USER: Then proceed with booking on 03/21 and 03/23.

ASSISTANT: May I know your airport codes please?

USER: My travelling airport codes are SFO and BOS.

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT: There is no flight on your desired dates.

USER: That is fine. Thank you for your response.

ASSISTANT: Thank you for reaching us.