i got an electric shower and live in an area with bad limescale (soft?)

anyway, the fukka blocks up every 2 mins with bigish bit of scale, and now the other day it just went red hot, then freezing cold then red hot, freezing cold etc etc, so smaked the coont and it tripped the leccy off

anyway, if i have a go at ripping it off the wall, whats the best way to descale it?

ive got a fookin big mallet if thats any good?