You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Richard Miller.

ASSISTANT: How may I lend a hand to?

USER: Can you please change my existing reservation as my plan to go for holiday trip got postponed?

ASSISTANT: Richard Miller, I am willing to help you for this. Let me check your reservation status in our database.

USER: Ok.

ASSISTANT: Richard Miller sorry to inform, no reservation is found with your criteria.

USER: It's ok, no problem. Thank you for the information.

ASSISTANT: Thank you very much for utilising our agency.