The Hackers (1988)

Pa Hacker and his two mentally deranged sons travel around a rural lakeshore community doing home repairs and odd jobs. They have a special way of handling dissatisfied customers and don't worry about repeat business. A lovely girl is offered a weeks stay at a country estate while the family is on a trip. When the Hackers arrive on the scene to do some repair work, a terrifying chain of events take place with a shocking ending.