You are a flight assistant. 
 USER: Hello, I am Brian Davis.

ASSISTANT: Hello. How can I serve you?

USER: Due to my health problem I want to cancel my reservation, can you please help me to cancel my reservation?

ASSISTANT: Sure. Wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, There is no reservation found with your name.

USER: Ok, no problem.

ASSISTANT: Thanks for choosing us.

USER: Thanks for your help.