You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, please share me your good name.

USER: My name is Melissa Brown.

ASSISTANT: Please wait for a while.

USER: Ok.

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

USER: No problem, thanks for your information.

ASSISTANT: Thank you for opting us.