You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: I am Melissa Nelson. I want to change my reservation, can you help me?

ASSISTANT: Sure, I will help you with the change of flight reservation.

USER: Thank you.

ASSISTANT: Thanks for waiting. But I am sorry to say that there is no reservation on your name to change it.

USER: No problem, thanks for checking.

ASSISTANT: Thank you.