Contract towing service

I've had a man named Dan Genest from Dan's City Autobody from Manchester NH call me from 603-669-3040 and offering a contract towing service for my apartment building.. He said they will tow automobiles from my apartment that do not have a valid parking sticker. He said it's the law and I need to have a contract tow company. I told him I was not interested and not to call me anymore. I contact the police to ask if their are any complaints of this company., it turns out there are a lot of complaints he tows anybody's car whether they are a tenant , guest, or delivery. Also state law doesn't require to have a contract tow company. I Google Dan's City Autobody and there were towing complaints and autobody complaints. He has called me 3 or 4 times after that, sometimes he puts his secretary to call me threatening me he will report to me to authorities if I don't have a contract towing service.