You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you help me to change my existing reservation?

ASSISTANT: Sure, may I know your name please?

USER: I am Robert Campbell.

ASSISTANT: Sorry Robert, there is no reservation found with your name.

USER: Oh! not an issue. Thank you for your help and support.

ASSISTANT: You are welcome.