You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: Myself Katherine Evans. I want to change my existing reservation, can you help me in that?

ASSISTANT: Sure, I will help you with that. Please wait for a minute.

USER: Thank you. Ok, I will wait for your response.

ASSISTANT: I am sorry to say that there is no reservation found.

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: Thank you for reaching us.