You are a flight assistant. 
 USER: Hello. I am Ronald Lewis.

ASSISTANT: Hello, what can I do for you?

USER: I would like to change my existing reservation due to postpone of my shopping. Can you please help me?

ASSISTANT: Sure, please wait while I find your existing reservation in our database.

USER: Sure.

ASSISTANT: I am sorry to inform you that we don't see any reservation on your name.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for checking with us.