You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Anthony Collins.

ASSISTANT: Good evening, how may I help you?

USER: Can you change my existing reservation to new dates?

ASSISTANT: Sure, just a second please.

USER: Sure.

ASSISTANT: I am sorry Mr. Anthony Collins, no reservation found on your name. Do you have any other requirements?

USER: It's ok, It might not be done properly when I was booking my ticket. No, you have given enough information. Thank you for checking.

ASSISTANT: Thank you for reaching us.

USER: Welcome.