You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Samuel Clark.

ASSISTANT:  How can I assist you?

USER: I want to change my existing reservation as my trip got postponed. Please help me out.

ASSISTANT: Ok, please wait I will revert you in a moment.

USER: Ok, take your time.

ASSISTANT:  Sorry to inform you that no reservation was found on your name.

USER: No problem, thanks for the information.

ASSISTANT:  Thank you for availing us.