You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, may I know your name to check for the previous reservation?

USER: Melissa Phillips here.

ASSISTANT: Please allow me a moment while I check for the reservation status.

USER: Ok.

ASSISTANT: Melissa Phillips, there is no reservation found under your name.

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

ASSISTANT: Thank you for contacting us.