You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: Please help me to change my recent reservation.

ASSISTANT: Sure. May I know your name to check with existing reservation?

USER: I am Helen Jackson.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: There is no reservation found under your name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for choosing us.