You can probably google the company and come up with an address, but whether or not that would be a good address is another story.
What I do when collectors call, after their done with their initial spiel, is ask them for the address where cease and desist letters should be sent. They are required to give you this information.
Then send a letter demanding that they cease and desist all further communications with you, at your phone number or address, regarding any accounts of your ex-husbands. Keep a copy for yourself, and go with certified mail if you want to be extra sure of things.
This should do the trick although, admittedly, it is much more than you should have to do in the first place. As soon as you told them that you didn't have any contact information they should have left you alone.
Best of luck!