You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I want to change my reservation as I am sick.

ASSISTANT: Sure, I am at your service to help you. Can you please provide your name?

USER: My name is David Perez.

ASSISTANT: Sorry David, I have not found any reservation under your name in our database.

USER: No problem, thank you.

ASSISTANT: It's my pleasure.