You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation to some other dates. Can you please help me with this?

ASSISTANT: Sure, may I know your name?

USER: Sure, I am Thomas Thomas.

ASSISTANT: Sorry, there is no reservation on your name.

USER: Ok, Thank you for your help.

ASSISTANT: Thank you.