You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I am Gregory Hall. I made a reservation earlier in the wrong date unknowingly so, I want to change my existing reservation. Can you please help me with this?

ASSISTANT: Yes, I can help you.

USER: Thank you.

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

USER: No problem, thank you for your information.

ASSISTANT: Thank you for contacting us.