AFNI Collections Collecting On A Debt I Don't Owe Victim of "family" identity theft- what to do now? Bloomington Illinois

About a month ago I received a letter stating that AFNI was collecting on a bill dated May 25, 1999 for Verizon. The letter stated they were trying to collect a debt of $315.72. The telephone number and address referenced in the account is a place that I have never lived... in Virginia. I have either lived in Philadelphia or Florida my entire life, and was indeed in high school (10th grade) in Florida at the date of the bill.

I called AFNI to inform them of this information. The representative informed me that I'd need to send a copy of my birth certificate and ID card to them to verify this. I didn't feel comfortable sending this information in the mail because it seemed my identity has already been compromised. I told them this.

Now, I have received another letter from AFNI, including a copy of the supposed bill that I owe, with the address in Virginia and the amount. This is supposed to mean what? That now I pay? The address on the bill is one of a family member who has since passed away. She must have used my name and social, but there's no way to make her pay the debt, and AFNI won't get off my back, so what do I do?

Peeved
Homestead, Florida
U.S.A.