You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: I am Sandra Mitchell. i would like to change my existing flight reservation. Could you help?

ASSISTANT: Sure, please hold on for a moment, let me check.

USER: Sure, please take your time.

ASSISTANT: Sure, can I know your preferable dates?

USER: I am going on 09/25 and return back on 09/27.

ASSISTANT: Ok, can I know your airport codes?

USER: I am going to HOU from MSP.

ASSISTANT: I found a flight 1027 of AA airlines matches with your preferences, can I proceed?

USER: Yes, please proceed.

ASSISTANT: Your ticket is booked.

USER: Thank you for the help.

ASSISTANT: Thank you, have a good day.