You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, How can I assist you?

USER: I am Betty King. I need to change my existing  reservation .Can you help me?

ASSISTANT: Sure, Wait a moment I will get back to you.

USER: OK.

ASSISTANT: Sorry, We did not found any reservations with your name.

USER: OK,Thanks.

ASSISTANT: Thanks for choosing us, Have a nice day.