You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: Can you please help me in changing my flight ticket modification?

ASSISTANT: Sure, I am happy to help you. Can I know your name?

USER: Thank you and my name is Thomas Turner.

ASSISTANT: Sorry to say that, no reservation found on your name in our database.

USER: Ok, that's fine. Thank you for your help.

ASSISTANT: Thank you for approaching us.

USER: Welcome.