You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I render you today?

USER: William Jackson here.

ASSISTANT: Ok.

USER: I want to cancel my active reservation because my trip dates are postponed, can you help me?

ASSISTANT: Sure, I will help you with that.

USER: Thank you for your positive response.

ASSISTANT: Please wait a moment.

USER: Ok, take your own time.

ASSISTANT: Thank you for waiting. I have checked in reservation list to cancel your ticket, but could not find any reservation with your name.

USER: It's ok, not a problem. Thank you for checking.

ASSISTANT: Thank you for choosing us.