Shocking service - incorrect diagnosis

No hot water Thursday morning, so logged callout with Flink Dink plumbers; plumber eventually arrived during load shedding at 4pm, but agreed to return. After reminders next day to the office (who maintained we had cancelled, due to load shedding!), plumber arrived late afternoon. He said that the geyser was leaking and had to be replaced (through the roof). I told the office that I would be requesting a second opinion and was immediately told to pay the R800-odd callout fee. By contrast, Electro Surgeon/Drain Surgeon subsequently arrived on schedule and saved the day by simply replacing the thermostat and a dripping valve. No need to replace the geyser at all! They even gave me a pensioner's discount.