You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,. How can I assist you?

USER: This is Lisa Jones and I want to change my existing reservation. Can you please help here?

ASSISTANT: Sure, please standby.

USER: Sure.

ASSISTANT: Thanks for your time, there is no reservation found with your specified name.

USER: No problem. Thank you for checking it.

ASSISTANT: Thanks for approaching us.