You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you today?

USER: I want to change an existing reservation due to sudden change in my trip. Can you help me?

ASSISTANT: Sure, please share me your good name.

USER: Ronald Roberts here.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: No issue. Thank you.

ASSISTANT: Thank you for opting us.