You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I aid you today?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Melissa Turner here.

ASSISTANT: Please wait for a minute.

USER: Sure.

ASSISTANT: I am sorry to say that there is no reservation found under your name.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.