Get a lawyer and contact your states attorney general to report them. First demand a copy of all work orders from the work they did. If they refuse then definately get a lawyer. But tell them youre going to get a lawyer and that youve reported them to the Attorney General. If they are trying to scam you theyll hopefully back off. If they really think theyve dine wirk for you its possible someone used your address and/phone number and name to avoid paying themselves. At least consult a lawyer to get an idea how to proceed.
If you have evidence disputing their claim, you should present it to them, after creating a form of backup or documenting your evidence in something like a video or photograph. If they still insist on charging you, get a lawyer and inform the police.