You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, may I know your name for the changing purpose?

USER: I am Kevin Mitchell.

ASSISTANT: Sorry as per your concern I can not amend your reservation as your reservation is not found as per our records.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Welcome, thank you for reaching us.