You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Nicholas Robinson. I want to change my existing reservation due to sudden change in my trip dates. Can you please help me with this?

ASSISTANT: Sure, please wait a moment.

USER: Sure.

ASSISTANT: Sorry, no reservation found on given name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching us.