You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I want to change my trip details in the past ticket which is booked in the last week, can you please help me in changing?

ASSISTANT: Sure, I will help you out.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: My name is Carolyn Walker.

ASSISTANT: Ok, please wait for a while.

USER: Sure, take your own time.

ASSISTANT: Sorry there are no reservations found.

USER: It's ok, anyway's thank you for checking.

ASSISTANT: Thank you for choosing us.