Qwest Repeated Billing for non-existent account; No credit for disconnected service; Seattle Washington

I had a DSL internet & phone bundle with Qwest from Nov 2006 - Apr 2008.

I switched over to another Internet provider(Charter Cable) in mid-April 2008 and also switched over to Vonage, the VOIP based phone service. They have the number portability service where they can transfer your existing phone number to their service. To do this, they(Vonage) directly do the switch and let me know once the switch is complete. My switch was complete by April 15 2008.

Then I called Qwest to cancel my phone AND DSL internet service. The customer service rep confirmed all of this and told me I'll receive a prepaid box for sending Qwest back the DSL modem I had rented from them and I'll get a "final bill" within 2-4 weeks.

The prepaid box for the modem arrived, I duly shipped the modem back and I thought the matter was closed.

Imagine my surprise, when I start receiving bills for a COMPLETELY NEW phone number with fresh monthly charges(for Broadband, Long Distance etc).
I called Qwest that there has been some mistake and that I never had this NEW account. I told them about the cancellation, the mail-back of the modem etc. with details about my old account. The rep confirmed the receipt of my DSL modem and said that she'll make sure that there's a back office request put in to cancel this new account and that I'll receive a "final bill" for this new account.

I even paid some outstanding charges(which I never understood; My bills were autopaid from my bank account; I had paid my bills in FULL for April AND May; I disconnected service Apr-15; yet I never received a final bill with a credit for the months of May and half of April). But the bills kept coming(with increasing amounts) for the new phantom account. The funnier thing is that these are all disconnect notices threatening to disconnect service yet Qwest never seems to disconnect, but only hit me with a larger bill for an account I never had.

I kept calling about Qwest twice a month(never could get the same customer service rep, always had to repeat my story); they'll say that there's been a mistake and will promise that it will be sorted out very soon. I got tired of calling them with absolutely no response other than a bill. Now it is Nov 2008, 6 months since I first disconnected from Qwest.

I've gotten tired of calling Qwest and am at a loss as to what to do. I'm not sure if I want to sue them for the $300 or so for the they're hitting me with an account I never had, as well as the $100 or so they owe me. Any advice for me? Qwest doesn't seem bothered by my calls so I'm not sure about my course of action here.

I have excellent credit and don't want it ruined by an unscrupulous company reported fraudulent charges.

Any advice appreciated. Thanks for your time & patience.

Anantha
Grants Pass, Oregon
U.S.A.