You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

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

ASSISTANT: Let me know your name.

USER: My name is Daniel Smith.

ASSISTANT: Sorry, no reservation found by your name.

USER: Ok, that's not a problem.

ASSISTANT: Thank you.

USER: Thanks for your information.