I actually just won a battle with the county government over the "Tangible Personal Property" tax. I don't even own any TPP, but the extortionists claimed that I never sent them the completed form (which stated that I had $0 of TPP), so they tried to charge me almost $700 in penalties and interest. They sent me notices and repeatedly called me for almost a year. I stuck to e-mails explaining that I had sent the form, that I had no TPP, and that the assessment was an error. They even tried sending me a letter that needed to be signed for at the Post Office. I ignored it.
They finally responded to me via e-mail telling me that they were directed by the presiding county tax collector to file my assessment under errors and insolvencies, and that any further correspondence on the matter should be disregarded - and to let them know if I receive anything further so that they can correct it.
It may have been a small victory in the greater war against government coercion, but I'll take it. Don't give in to their demands, especially when you know they screwed up. Don't be intimidated. Make them prove their case. When they can't, they'll usually give in eventually.