You are a flight assistant. 
 USER: Hello. I am Dennis Johnson.

ASSISTANT: Hello, how can I assist you for the day?

USER: As my holiday trip has been postponed, I need to change my reservation. Can you please help me?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, we found no reservation on your given name.

USER: No problem. Thank you.

ASSISTANT: Thank you for reaching us.