You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, what service do you need from us?

USER: I want to change my reservation due to health problem, can you help me?

ASSISTANT: Ok, please tell me your name to check the reservation.

USER: Myself Lisa Johnson.

ASSISTANT: Ok, sorry to inform you, there is no reservation with your name.

USER: No problem, thanks for checking.

ASSISTANT: You are welcome. Thank you for reaching us.