Reno, they may be adding interest and this interest is only showing up each time they update. Like it or not, CA's can continue to charge interest. I know they can do this on accounts that originally had interest, anyway (CC's, loans, etc.), but, as far as I know, they can't add interest to an account such as a utility bill (although they may be able to continue adding late fees). I could be wrong on this, however, so don't take my word for it.
I have been surprised by the number of posts I have seen about people having trouble with Asset Acceptance. They had a couple accounts for me, which I disputed with the CRB's, and they were all dropped on all 3 CR's after my first dispute attempt. Yes, I am knocking on wood right now--I am waiting for the day that all of the deletions I have achieved in the past couple of months start reappearing.