It’s really a difficult situation, but the local council is unlikely to cooperate, unless there are special circumstances involved, such as your building being part of, or beside, a commercial centre. If you think about it, the only thing the parking inspectors can police is time restriction, such as not occupying a parking bay for more than 24 hours? All they have are car registration numbers, and this cannot separate real visitors, from resident’s and stranger’s cars. This is only a minor problem with visitors parking, and the major problem is with residents parking their (2nd) cars there, or people using it who are not actually visitors to your building.
In our building we improved a similar situation a lot by installing a boom-gate to allow access to the visitors parking bays. A visitor must have a building access fob, or buzz a Unit in the building, to get the boom gate to open. Along with CC TV cameras, and an active strata committee, this has cut the inappropriate use of our visitors parking area a lot. But your building may not have a suitable access system in place, nor a CC TV system? In that case, I’d suggest you arrange a security company to put together a proposal to upgrade your building’s security, by installing a boom gate to limit access to the visitors parking, and to upgrade the building’s security generally, with an electronic access system, an up-to-date intercom system that can operate the boom gate and entrance doors remotely, and a CC TV camera system covering the common areas, including the boom gate, driveways and visitors parking areas.
You seem to have a lot of visitors parking bays (40) so you should check the building’s Development Application, and with the local Council, to see if that number are all mandated legally. If not, then you have an option, once you get a boom gate, to lease a few of the bays to residents, or other people, which could help with the costs of this upgrade.