You are a flight assistant. 
 USER: Hi, I am Sandra Taylor.

ASSISTANT: Hello. How may I help you today?

USER: Can you please be my helping hand in changing my existing reservation?

ASSISTANT: Sure, please wait a moment I will check the reservation status.

USER: Ok.

ASSISTANT: Thank you for waiting, we are happy to inform you that there is a reservation by this name. Could you please let me know your updated travelling dates?

USER: My trip dates are 03/19 - 03/21.

ASSISTANT: May I know your source and destination points ?

USER: My airport codes are from New York, NY - JFK to Phoenix, AZ - PHX.

ASSISTANT: Thank you for sharing your journey details, unfortunately there are no flights found with your updated journey details.

USER: Not an issue, thank you for your best service.

ASSISTANT: You're welcome. Thank you for availing us.