You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to change my recent reservation as my joining date got postponed. Can you help me in changing?

ASSISTANT: Please provide me your name so that I can check with the system.

USER: My name is Janet Mitchell.

ASSISTANT: Give me a moment.

USER: Sure.

ASSISTANT: Janet Mitchell, I regret to inform that there is no reservation by your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us.