You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I want to change my reservation, can you please help me to modify my travel dates?

ASSISTANT: Sure, may I know your good name please?

USER: My name is George Brown.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: Ok, not a problem. Thank you.

ASSISTANT: Thank you for choosing us.