Same thing. I notified TW to disconnect Oct 2008. This is July 2009 and they are still billing me, now over $600.
I have called every month and get the same pat answer, we will take care of this. Today I got the same answer but said they are charging me $50 for the modem they never picked up. My lease expired in Oct. I don't have any idea where their modem is. This is definitely their problem, I told them, and I will not pay them.
Figure this each 100, 000 disconnects x $50 = $5, 000, 000 windfall for TW cable - criminal.