You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Myself Melissa Carter.

ASSISTANT: How can I assist you today?

USER: I want to change my existing reservation, can you help me in that?

ASSISTANT: Sure, will you please give me a moment?

USER: Thank you.

ASSISTANT: Thanks for waiting, there is no reservation found under your name.

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: Welcome, have a great day.