You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Janet Roberts.

ASSISTANT: What can I do for you now, Janet Roberts?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Ok, I will help you in that. Thanks for waiting. We did not find any reservation on your name to change.

USER: Ok, no problem.

ASSISTANT: Thank you for choosing us.

USER: Thanks for your information.