You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Actually my exam is postponed so that I want to cancel my recent reservation , can you help me?

ASSISTANT: Sure, I can help you with that. Please let me know your name please?

USER: Yes, I am Johnathan Adams.

ASSISTANT: Sorry Johnathan, there is no existing reservation with your name.

USER: Thank you for your help.

ASSISTANT: Thank you for choosing us.