You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I wanted to change my reservation due to my planned program got postponed. Can you help me with this?

ASSISTANT: How can I help you? Sure. Can I know your name please?

USER: I am Gregory Collins.

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

USER: It's ok. Thank you.

ASSISTANT: Thank you and have a nice day.