Showers with prioity switch not working

Hi all,

I need some advice with my faulty shower.
We have in our home 2 electrical showers and a priority switch.

We tried to use 1 shower and it did not work, but the light for Power was on, if you push the button to use it, the light goes off, but shower doesnt work. seems like electricity is getting there.

In the other shower, the second in priority, no light at all.
Would you be able to help me finding out if the priority switch would be the problem? it is 3 months old.

Every electrician I call is busy or think my home is too far. Portarlington
So Im thinking of buying a electrical test meter and check the switch. I used to install alarms back in my home country, but try to avoid at all cost anything out of my league as cheap costs double :-)