While providing services on two occasions, the contractor caused damage to the landscaping, rolling over markers set up to define the edge of the drive, tearing up lawn and destroying shrubs. He also failed to clear the entire drive. When he showed up a third time, I immediately informed him that I would not be using his services. He left, then returned seven minutes later, started plowing anyway, and refused to leave after I informed him he was trespassing and needed to leave. In the process, he again did damage to the lawn while veering off the driveway, and left the drive and walkways unfinished. He is now demanding payment in full for the prior services and for the unauthorized service. I am proposing to pay for two services, withholding the third to compensate for the damage done to my landscaping, and the final one as it was not authorized. He is threatening to file a lien against the property. Am I correct in believing that a lien cannot be filed (in Wisconsin) for routine maintenance services such as snow removal?