You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how can I provide assistance to you?

USER: My name is Elizabeth Davis. Please change my existing reservation.

ASSISTANT: Sure, I am mirthful to help you. Please stand by.

USER: Ok.

ASSISTANT: Thanks for waiting. There is no reservation found on your name.

USER: Thanks for the assistance.

ASSISTANT: Thanks for opting us.