You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Gregory Walker.

ASSISTANT: How can I assist you Walker?

USER: Due to health problem, I want to cancel my reservation.

ASSISTANT: Ok. Give me a moment, while I check for the reservation on your name.

USER: Ok.

ASSISTANT: I had found reservation on your name. Your reservation has been cancelled successfully.

USER: Thank you for helping me.

ASSISTANT: You are welcome. Take care of your health.

USER: Thank you for the advice.