You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I aid you?

USER: I am Andrew Perez, want to change my existing reservation, because there is sudden change in the program.

ASSISTANT: Sure, I will help you.

USER: Ok.

ASSISTANT: Could you please tell me your name?

USER: I have mentioned it already.

ASSISTANT: Sorry, no reservation found with your name.

USER: Thanks for the information.

ASSISTANT: Thank you for approaching us.