You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

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

ASSISTANT: Ok, may I know your name please?

USER: Yes, I am Brenda Clark.

ASSISTANT: Sorry Brenda, unfortunately there is no reservation found under your name in our database.

USER: Ok, thank you for your help.

ASSISTANT: Thank you for choosing our service, have a good day.