You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you today?

USER: I am Virginia Taylor. I need to change my existing reservation, Can you please help me with thta?

ASSISTANT: Ok, please wait for a moment till I check with your previous reservation.

USER: Sure.

ASSISTANT: Thank you for waiting for my response. I'm so sorry to inform you, that there is no reservation found under your name.

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

ASSISTANT: Thank you for choosing our services. Have a great day.