You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: My name is Eric Green.

ASSISTANT: How may I help you?

USER: Can you help me in changing my existing reservation?

ASSISTANT: Sure, I will help you. Ok, wait for a minute.

USER: Ok, take your time.

ASSISTANT: Sorry to say that, there is no reservation found on your name.

USER: Its ok, thank you for the information.

ASSISTANT: Thank you for reaching us.