Hello guys

It's been a while since I posted anything...I need help asap. A new domestic installation has main building with Main DB and back rooms with Sub DB. Both buildings have 3kW geysers installed....
Now a client has been complaining about getting shocked when taking shower on either one. Hot and cold water pipes are bonded to earth. Every extrenous conductive parts are bonded to Earth.

I did insulation resistance test on Geysers elements... not down to Earth, a RCD is not tripping neither. I tested shower tabs with water on the floor and get 36Volts which I think its dangerous too. Isolated all other earth connections except for geyser, still got shocking voltage. Went on to test an Elevated Neutral Voltage on supply, with MCB off...got 32V on both buildings because B/rooms are looped on supply.

LV Earthing System should be TN-C-S as I saw it on authority post (3phases with PEN conductor)
I'm puzzled as to what would cause Voltage on Earth Terminal and anything that is bonded to it.

I'd appreciate it very much if I could get help, or an insight guys. I'm really stuck