You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: My name is Katherine Robinson. I need to change my existing reservation, could you please help me with that?

ASSISTANT: Sure. Please give me a second.

USER: Sure.

ASSISTANT: There is no existing reservation with your details.

USER: That's ok. Thank you for the information.

ASSISTANT: Thank you.