You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you out?

USER: Will you please change my existing reservation as my plan to meet my friend got postponed?

ASSISTANT: Sure, I will help you in changing the reservation. May I know your name please?

USER: I am Nicholas Mitchell.

ASSISTANT: Sorry, there are no reservations found in our database.

USER: It's ok, not an issue. Thank you for your response.

ASSISTANT: Thank you for reaching us.