I agree that a certified, return receipt required and notarized letter be sent to their Headquarters and addressed to the President. When you return the hardware they will give you a receipt at the offices on 441 but they will tell you they cannot cancel service and you must call that into the company. In the letter should be copies of the receipts for the return of the hardware and that service was cut off at the date a new service was brought in or Comcast canceled. At this point you will have to monitor any billings received and return them with the confirmed signed return receipt from their Corp Offices.
A problem we had was that I had returned their modem etc and had a receipt and bought one for the new carrier (e.g. DirectTV) and continued to use Comcast internet. As you would guess I continued to get billing for a "rental
Modem" and had to remind them that I owned ours and they should cease and desist from sending us rental bills for a modem,etc. So far they have.
