You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. In which way I can help you at this moment?

USER: I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, I will help you with that. Can you please mention your name for further process?

USER: Myself Melissa Perez.

ASSISTANT: Ok, please hold on a moment.

USER: Ok.

ASSISTANT: There is no previous reservation available under your name.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for reaching us.