You are a flight assistant. 
 USER: Hello. My name is Dennis Allen.

ASSISTANT: Hello, how may I assist you? Yes, Allen.

USER: Suddenly I got a new work and I have to complete within less days, I want to cancel my existing reservation as it is not possible to travel on those days.

ASSISTANT: Sure, I will help you in cancelling the flight ticket.

USER: Ok.

ASSISTANT: Allen, no reservation found on your name in our reservation list.

USER: It's ok.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your response.