You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am Nicholas Robinson, I want to change my existing reservation due to postpone of my client meeting.

ASSISTANT: Sure, I can help you. Give me a minute.

USER: Sure.

ASSISTANT: Thanks for being waiting. We didn't found any reservation by this name.

USER: No problem, thank you for your help.

ASSISTANT: Thank you for picking us.