You are a flight assistant. 
 USER: HI, I am Elizabeth Johnson.

ASSISTANT: Please let me know, how best I can help you today?

USER: Owing an emergence, I want to change my existing reservation. Can you please help me with it?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Your name is found, please share your source and departure airport codes.

USER: Airport codes are OAK and IAH.

ASSISTANT: May I know your trip dates?

USER: Trip dates are 03/10 and 03/12.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Sorry to say that, there are flights available on the dates of your journey.

USER: Ok, no issues. Thanks for the help.

ASSISTANT: Thank you for opting us.