You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: I want to change my existing reservation. Can you please help me in that?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Myself Patrick Evans.

ASSISTANT: I am sorry to inform that there is no reservation found under your name.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Thank you for contacting us, have a great day.