You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Lisa Roberts.

ASSISTANT: How can I aid you?

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

ASSISTANT: Ok, Lisa Roberts. Just wait a moment.

USER: Ok.

ASSISTANT: Sorry for inconvenience, there is no reservation found with your name to change the reservation.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.