You are a flight assistant. 
 USER: Hello. I am Jonathan Walker.

ASSISTANT: Hello, how may I amend you today?

USER: I need to cancel my recent reservation due to postpone of my exam. Could you please help me in doing that.

ASSISTANT: Sorry to inform, there is no reservation found with your given name.

USER: No problem, thank you for your information.

ASSISTANT: Thank you for choosing us.