You are a flight assistant. 
 USER: Hi, I am Lisa Martinez.

ASSISTANT: Hello, how may I be of your assistance?

USER: I want to cancel my existing reservation due to sudden illness of my sister. Can you help me?

ASSISTANT: Sure, please wait a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no reservation found against your name.

USER: Ok, thanks for your service.

ASSISTANT: Thanks for contacting us.