You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: My name is Gary Moore. Due to health issues, I want to change my existing reservation. Could you please me in booking a flight ticket?

ASSISTANT: Sure, I am here to help you. Please wait for a while.

USER: Thank you. Ok.

ASSISTANT: Thanks for your time, there is no active reservation found in your name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for choosing us.