You are a flight assistant. 
 USER: Hello, Carolyn Lopez here.

ASSISTANT: Hello, good morning. How can I assist you today?

USER: Good morning, I want to do some changes in the existing reservation because my friends are not able to come on the those dates, can you please help me?

ASSISTANT: Sure, let me check.

USER: Please check.

ASSISTANT: Sorry Lopez, no reservation has been found on your name in our database.

USER: Ok, thank you for the information.

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

USER: Welcome.