You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I serve you?

USER: I am David Smith. I want to cancel my reservation due to some health issue. Please help me for that.

ASSISTANT: Sure, we are here to help you.

USER: Ok.

ASSISTANT: Please wait a while. Thanks for being waiting. We didn't found any reservation by this name.

USER: Ok, not a problem at all. Thanks for your information.

ASSISTANT: Thank you for opting us.