About a month ago, my geyser tripped my main leakage switch on the circuit board. A plumber came and replaced the element and thermostat and an electrician came and bypassed the municipal geyser /electricity setting.

Ever since, I only get about 3 minutes of hot water, after which it progressively goes colder. In about 6 minutes it's only child water coming out.

The element and thermostat has been replaced twice and the pressure valve outside my unit as well. There doesn't seem to be a leak anywhere either. Yet still my problem continues.

Any advice would be appreciated since the plumbers are all at a loss as to how to fix this. Is this a electrical problem? A geyser problem? Please help?