You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation due to some technical issues. Can you help me?

ASSISTANT: Sure, may I know your good name?

USER: Sure, I am Helen Lewis.

ASSISTANT: Sorry to say that, no reservation was found with your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for opting us.