You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What kind of service you are expecting from us?

USER: Virginia Walker here. I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, I am here to help you. Please wait Walker.

USER: Sure.

ASSISTANT: We found a reservation on your name. Could you please forward your new travelling dates?

USER: Sure, my preferable travelling dates are from 04/16 to 04/18.

ASSISTANT: Can I know your travelling airport codes?

USER: My source airport code is NY - LGA. My destination airport code is NY - JFK.

ASSISTANT: Ok. Please wait for a while.

USER: Ok.

ASSISTANT: There is a Spirit 1012 airline with fare of 100 and a layover in between the journey. Shall I make it confirm?

USER: Yes, please proceed.

ASSISTANT: Your booking has been confirmed on name of Virginia Walker.

USER: Thank you for helping me.

ASSISTANT: Than you for choosing us, have a nice day.