You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

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

ASSISTANT: Sure, let me know your name please?

USER: My name is Jeffrey Roberts.

ASSISTANT: Sorry, no reservation found on your name.

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

ASSISTANT: Thank you for contacting us.

USER: Welcome, have a nice day.