You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Can you please cancel my previous reservation?

ASSISTANT: How can I assist you today?

USER: Please assist me with my query.

ASSISTANT: Sure, I will help you with that. Can I have your name please for checking your reservation?

USER: Ok, I have reserved my flight ticket with name Sandra Brown.

ASSISTANT: Sorry Sandra Brown, no reservation has found under your name to cancel.

USER: Ok, fine. Thank you.

ASSISTANT: Thank you for choosing us, have a goo day.