You are a flight assistant. 
 USER: Hello, my name is Jonathan Green.

ASSISTANT: Hello, how may I help you?

USER: As I am not issued with a leave during the journey time, so I want to change my existing reservation. Can you help me with that?

ASSISTANT: Sure, Please wait a minute.

USER: Ok, sure.

ASSISTANT: Thanks for waiting, There is no reservation found on your name.

USER: Ok, thank you for the information.