What if the property company starts to use the owner's house without using it?

No, these are two different things. If the property service is not in place, they can complain to the Housing Authority, or bring a lawsuit to the court according to the property service contract, and they will deal with the property company. The property management fee is the property management fee of the whole community. You can't refuse to pay the management fee. There are special regulations. Property management is a service to the community. Your house belongs to your exclusive part and is your personal property. Unauthorized occupation without your consent is an infringement of your ownership. According to Article 39 of the Property Law, "the owner has the right to possess, use, profit from and dispose of his own real estate or movable property according to law". Ownership is exclusive, and no individual or unit may infringe upon it without consent. You can ask the property company for compensation, or you can bring a lawsuit directly to the court.