If all they are doing is sending bills, I would suggest refusing delivery for the next few and see if that doesn't get their attention. If that fails to work, I would suggest sending a demand for verification of the debt under the fair debt collection practices act, and see if there is a response.
If all that fails, I would suggest simply discard the bills (but be careful to insure they are just bills!) If the creditor sues, you most likely have a good defense but if you fail to raise it because you've thrown away the lawsuit, you place yourself at risk.
I would urge you to consult with a local attorney to insure you handle this properly, however, unless and until they take things further than merely mailing a bill, I don't believe much more one your part is appropriate.
Previous poster got this just right. You are under no particular obligation to respond, so long as you have given proper notices. I had a probate once where I had a bank personally served with the Notice of Probate, just in case (I did not know whether they were a creditor, just had a hunch) and had the Notice published, and they did not contact me for two and a half years. I thoroughly enjoyed writing that letter telling them they had left it too long.
Hope this helps. Elizabeth Powell