Sling TV Cancellation policy is horrible, canceled on 7th day but not before exact time the trial started Englewood Colorado

On Thanksgiving day, my Direct TV box broke and I started a 7-day free trial of Sling.  The next Thursday, after work, I canceled.  To my horror, I was already charged $60 earlier in the day.  I contacted customer service and was told that I had to cancel before the exact hour/minute that I started the trial.  This is not clear when you start the trial.  I asked if I could just be charged 1 day for the service, since I didn't really like that service, but was told 'No - this is a prepaid service".  They told me my only option is to dispute it with my credit card company.  I am so upset about this, and feel like they prey on busy people who assume they have until midnight on the 7th day to cancel.  I will never sign up for Sling again because of this, and hope that enough people complain so that they change their cancellation policy.  I am doubtful my credit card will remove the charge, but I am definitely trying!