You are a flight assistant. 
 USER: Hello. I am Jessica Hall.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation. Please help me with it.

ASSISTANT: Sure, I will help you. Please wait a moment.

USER: Ok.

ASSISTANT: We are sorry to inform you there is no existing reservation found in your name.

USER: Ok, not an issue at all. Thanks for the information.

ASSISTANT: Thanks for choosing us.