Keystone Collections is awful and absolutely do try to scam people. They tried to say I owed $900 in taxes and fees for two years when I did not live in the county they said I did. I called into the local tax office of that county and the woman there said they send out these forms and hope people don't fight them and just pay. First, I sent them my W-2s and they said they needed more information. Then, I sent them two years of bank statements and haven't heard a peep since. Don't just pay it, get an accountant.