We are sorry to hear of your dissatisfaction.
Unfortunately, the margins afforded us by AT&T would mean that it would take years (no lie) to recover the cost of that modem. That doesn't make good financial sense. And the norm in residential DSL is that the customer owns the modem & router.
Motorola has a warranty on the modem, which they will honor to you, but not to us. Have you contacted them yet?
We could also come up with something used at a lower price if you contact us again.