You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Steven Evans.

ASSISTANT: Can you please tell me how may I help you?

USER: I want to change my existing reservation, could you please help me with that?

ASSISTANT: Ok, sure. Sorry to say, no reservation found on your name.

USER: That's ok.

ASSISTANT: Thank you for contacting us.

USER: Thank you for the help.

ASSISTANT: Have a nice day.