Sharraxaadda

The tenants at 2718 (a frat house) continually park in the church's parking lot, sometimes overnight. (The lot is clearly marked for church business only.) I've contacted the "resident assistant" and the owner without any improvement in the situation. The tenants and their friends are also leaving increasing amounts of trash in the parking lot. I'm not sure if the PROP laws are still in existence for nuisance rental properties. Can someone tell me what our options are? Thanks.