You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my existing reservation. Will you please help me in changing?

ASSISTANT: Sure, I am ready to help you. May I know your name please?

USER: My name is Kathleen Lewis.

ASSISTANT: Thank you, can you please wait for a minute.

USER: Sure.

ASSISTANT: Sorry to tell you, I cannot find any flight reservation with your details.

USER: Oh! it's OK.

ASSISTANT: Thank you Kathleen Lewis.

USER: My pleasure.