I've just paid out £126 for a re-conditioned calliper because of the electric brake. To cut a long story short , it was an accident , but wouldn't have happened with a manual handbrake. There is a fiddly procedure to de-activate during servicing and it involves holding the accelerator down. I became confused and pressed the brake pedal which resulted in a piston ejection!
Fuming. The procedure involves doing 3 things together which I'm never good at. A bit like rubbing your tummy and your head simultaneously!