How do I make a collections agency tell me who they are?

[politicat]

First, the bill is not mine. Someone gave my cell phone number as their own phone (probably trying to dodge just this situation). So I'm not getting the paper bills or the ding to my credit (I hope), just the calls.

They're calling 3 to 6 times a day, however, and since I'm NOT the person who owes the debt, they refuse to A) believe me when I say that I have no idea who X person is, b) take my cell phone off their lists, c) give me their mailing address so I can write them to demand they take me off their list, or d) identify themselves. I'm REALLY tired of it, and since it is a cell, they're eating into my minutes.

I wrote to my attorney general and gave them the phone number (the only data I have on the agency) but my state is in severe financial crisis, so I have no hope that the AG will be able to do anything about it. Reverse lookup on the phone numbers does not bring it up - I'm assuming a PBX.

I am getting stubborn about this - It's my phone number and I'm not changing it just to escape this misbegotten problem.

Any ideas?