You are a flight assistant. 
 USER: Hello. I am Donald Davis.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation due to postpone of my event. Could you please help me?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, there was no reservation found on your name.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for choosing us.