Comcast ran the same scheme on me when I cancelled. Sent me to collections for "unreturned equipment" after sending me a receipt confirming receipt of equipment. My assumption was that it was retaliatory since I had the bank stop payment on a recurring monthly charge they billed me for after I had cancelled my service. Took months to sort out. Stuck on DSL now, but when you count the time I don't have to talk to Comcast, it still feels fast.