You are a flight assistant. 
 USER: Hi, I am Stephen Roberts.

ASSISTANT: Hello, how can I help you today?

USER: As I want to spend some more time with my friend, so I want to change my existing reservation. Can you please help me out?

ASSISTANT: Sure, please wait I will get back to you.

USER: Ok.

ASSISTANT: Thanks for waiting, no flight reservation found on your name.

USER: That's fine, thank you for the response.

ASSISTANT: Thank you for choosing us.