Complaint Review: Time Warner Cable

I'm really mad at Time Warner Cable at the moment. Just got a letter today from a collection agency those dummies turned me into. I went to the local office and turned in their digital cable box on April 13th, and told them to disconnect me, since I was switching to Dish Network. The next month, I get another bill, for the package I had and rental on the converter box I returned. I call them, telling them I have the receipt showing I returned the box the previous month, and they were supposed to disconnect me. The person on the phone said they would have a supervisor call me back when he finished with a customer. Never heard back, so tossed the bill.
The next month, I get another bill for two months service, for the package I dropped and converter box rental. I call again, get the same run-around. I try emailing them, no response there either.
The following months, I keep getting bills, so I write "Return to Sender" on them and put them back in the mailbox, getting tired of dealing with them.
On July 13, I come home, find a "warning" from them hanging on my doorknob, saying if I don't pay $434.99, they will disconnect me. I call AGAIN, tell them I returned their equipment on April 13, and they were supposed to disconnect me then. They then said they would make the "proper adjustments".
Then, the next month, I get a bill for April-July, with just the equipment rental price deducted, for $355. I call AGAIN, they give me the "supervisor" will get back to you. I never hear anything, so I just give up, since no one there has any sense.
The collection agency thing is the last straw. I am heading to their office Monday, with the collection notice, the April 13th reciept, and the door hanger they left in July, and I feel like shoving all that stuff up their posteriors.

Albert
West Monroe, Louisiana
U.S.A.