You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am George White.

ASSISTANT: OK.

USER: I want to change my existing reservation. Please help me in changing reservation process.

ASSISTANT: Sorry White, unfortunately there is no reservation found under your name in our database.

USER: It's OK. Thank you for providing the information.

ASSISTANT: Thank you, have a great day.