You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation because of some personal work, can you please help me out?

ASSISTANT: Sure, I will help you in changing your reservation. Can I know your name please for checking your reservation status in our website?

USER: Thank you, my existing reservation is on the name of Catherine Perez.

ASSISTANT: Ok, please wait for a moment. I will check and get back to you.

USER: Sure.

ASSISTANT: Perez, I have not found any reservation under your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for contacting us and have a nice day.