To cancel your AT&T account you will need to call into support. But before, you should find another provider and check to see if your number is portable, meaning you can bring the phone number to another company.
The issue and preferred resolution, in GetHuman-patcadi's own words:
I want to cancel my subscription to sleep sling TV as of today. Will I receive a refund of unused portion of the payment I made for this month?
I trust that Sling TV will make this right and come up with a resolution that is fair.
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