You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I aid you?

USER: I am David Davis. Please help me with changing my reservation due to some changes in the plan of my trip with my colleagues.

ASSISTANT: Sure, we will help you.

USER: Thank you.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry to say you that there is no reservation found on your name to proceed further.

USER: Ok, no issue. Thank you.

ASSISTANT: Thank you for choosing us.