You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I need to change my existing reservation due to whether problem. Can you please change my existing reservation?

ASSISTANT: Sure, May I know your name please?

USER: Mary Lee is my name.

ASSISTANT: Ok, Mary Lee, please hold on a minute.

USER: Sure.

ASSISTANT: Thanks for your patience, we are sorry to inform you that no reservation has found based on your specified name.

USER: Ok, no problem. Thank you for your service.

ASSISTANT: Thanks for opting our service, have a pleasant day.