You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Gregory Campbell here.

ASSISTANT: Hello Gregory.

USER: Due to the cancellation of my sister engagement function, we like to cancel our recent reservation.

ASSISTANT: Sure, please wait for a moment, I will check your details.

USER: Ok.

ASSISTANT: Sorry Gregory, there is no reservation found on your name.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Welcome.