You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: My name is Anthony Smith.

ASSISTANT: Yes Smith, how can I help you?

USER: I want to do some modification in my existing reservation. Can you help me for that?

ASSISTANT: Sure, hold on for a moment. Let me check.

USER: Ok, please check.

ASSISTANT: Sorry Smith, there are no flights reserved on your name.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome. Thank you for choosing us.

USER: Welcome.