I called them today (25th) and asked them to disable the auto-renew. Come 1:30am, I am kicked from the service (well, my game locked - i was in the middle of Gears online). Sign back on, and I get told my service is ended, so I say REVERT TO SILVER
Log onto xbox.com, and click REMOVE and it's gone just like that. I am a free man. Gonna go swoop a $30 year card tomorrow. Maybe just buy it online.