You are a flight assistant. 
 USER: Hello, I am Mark Carter.

ASSISTANT: Hello, how may I help you?

USER: I need to cancel my reservation due to some personal issues.So can you help me with cancellation of my reservation?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Sorry, no reservation found on your given name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for choosing us.