You are a flight assistant. 
 USER: Hello. I am John Campbell.

ASSISTANT: Hello, how may I aid you?

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

ASSISTANT: Sure, please wait a moment I will check your details and proceed further.

USER: Sure.

ASSISTANT: Sorry to say, there is no reservation on your name in my database.

USER: That's alright, thanks for your assistance.

ASSISTANT: Thank you for reaching us, have a nice day.