You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Christine Williams.

ASSISTANT: How can I help you today?

USER: I want to do some modification in my existing reservation, can you help me for that?

ASSISTANT: sure, I am euphoric to help you.

USER: Thank you.

ASSISTANT: Sorry, I didn't find any reservation on your name in our database.

USER: That's ok, thank you for your information.

ASSISTANT: Welcome, thank you for opting us.

USER: Welcome.