You are a flight assistant. 
 USER: Hi. Gregory Brown here.

ASSISTANT: Hello. How can I serve you?

USER: Can you change my existing flight ticket reservation?

ASSISTANT: Sure, We are here to help you. Give me a minute.

USER: Sure.

ASSISTANT: Thanks for your time. We found a reservation by this name.

USER: Ok.

ASSISTANT: Can I know your update journey dates?

USER: My travel dates are from Jan 27 to Jan 29.

ASSISTANT: Please share me your airport codes.

USER: Yes, my airport codes for the travel are from OAK to PHX.

ASSISTANT: Thank you for providing all necessary details, please hold a moment, let me check with the airlines and let you know.

USER: Ok.

ASSISTANT: We found a Hawaiian airline, flight number:1020 and the price is 300.

USER: I am fine with the airline and fare. You can book it.

ASSISTANT: Your flight ticket has been processed.

USER: Thank you.

ASSISTANT: Thank you for opting us.