People without permits parking

Liverpool council spent days creating residents parking where I live which made my life so much easier (as I am disabled). The residents that now had somewhere to park were so happy. Now there are people that visit a certain house and sometimes stay over park wherever they choose a including outside my home and an elderly gentleman across the road. Sometimes there are 4 and 5 cars belonging to visitors at the address. At the moment there is a camper van parked up that doesn't have residents parking at all, taking the space of 2 cars. This is making a joke of all the hard work, time and money of Liverpool council. Is there anything that can be done about this please or do we have to start playing hunt a parking space again? Help would be very much appreciated with this problem.