You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Robert Campbell here. I need to change my existing reservation, can you help me in doing that?

ASSISTANT: Please give me a moment.

USER: Sure.

ASSISTANT: There is no reservation found with your given name.

USER: Ok, no issues.

ASSISTANT: Thank you.

USER: Thank you for the information.