With an online chat cancellation, they are supposed to send you an email with confirmation of the cancellation. Regardless, you always have the option to download a transcript of the online chat session in case you need proof of the cancellation. I believe that link is in the lower left corner of the Chat box. Also, after any online cancellation, if a Points Reservation, always check you Club Points balance afterwards to make sure the points were returned to your account. If not, then the cancellation probably did not go through correctly. You should also be able to confirm cancellation of a weeks or points reservation using the appropriate tabs on the MVC site (Use Weeks, Upcoming Reservations or Use Points, Points Reservations) or, in the alternative, checking under My Trips under your Bonvoy account to see if the reservation no longer shows up.