Over the years the Rain Director has been continually developed to assist with plumbers to remove airlocks.
As far as the system is concerned there is only one reason ( that is sytem related ) that the water is not making it’s way to the toilets. Apart from airlocks unfortunately any other issues are related to the plumbing which is the responsibility of the plumber.
Airlocks occur if the flow of water into the header tank is less than the flow of the water leaving the header tank.
The first thing to establish is when you purchased the Rain Director