You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you now?

USER: I want to change my reservation, can you please help me to modify my reservation?

ASSISTANT: Sure, I will help you with that. Can I know your name to check your previous reservation?

USER: My name is Thomas Perez.

ASSISTANT: Please be on hold.

USER: Sure.

ASSISTANT: We regret to inform you that, there is no reservation found on your name in our records.

USER: Ok, not an issue.

ASSISTANT: Thank you for approaching us, have a great day.

USER: Thank you for informing me.