You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I can help you with that. May I know your name?

USER: My name is Mary Lewis.

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

USER: Ok, not an issue. Thank you for providing information.

ASSISTANT: Thanks for choosing us.