You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: Could you please help me in changing my existing reservation?

ASSISTANT: Can I know your name?

USER: Sure. My name is Melissa Gonzalez.

ASSISTANT: Please hold on for a moment while I check for any active reservations with your name.

USER: Sure, take your finest time.

ASSISTANT: I am sorry, there are no reservations with your name.

USER: That's ok. Thank you for your valuable time.

ASSISTANT: Thank you, have a good day.