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

ASSISTANT: Hello, how may I help you?

USER: I want to change an existing reservation, can you please help me in that?

ASSISTANT: Sure, will please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: That's ok, not a problem. Thanks for your information.

ASSISTANT: Thank you for choosing us.