You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation as my plans to travel got cancelled?

ASSISTANT: Sure, may I know your name?

USER: Nancy Clark here.

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

USER: Ok, not a problem.

ASSISTANT: Thank you for choosing us.

USER: Thank you.