You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I aid you?

USER: As I am planning to attend a birth day function is got postponed, I want to change my existing reservation.

ASSISTANT: Ok.

USER: Can you help me with change reservation?

ASSISTANT: Sure, I am here to assist you. Can you please specify your name?

USER: My name is Steven Baker.

ASSISTANT: Ok. We found a flight on your name. So, now please send the current details of your journey.

USER: My airport codes are from LAS to ORD.

ASSISTANT: Ok.

USER: My travelling dates are from 12/20 to 12/22.

ASSISTANT: Ok. Please wait for moment.

USER: Ok.

ASSISTANT: There are no flights found on your current journey days.

USER: Ok, No problem.

ASSISTANT: Thanks for availing us, Have a great day.

USER: Thank you for the information.