how do i fix my triton jade electric shower?

My shower just recently wont turn on at all. First started when my flat mate went for a shower for about 30 mins, then turned everything off. I went in and no power at all. Next day I tried again and it was fine. Forgot about it then a week later it stopped working again.
I've noticed that the main power switch outside the bathroom turns on ok with light showing, but when i push the showers power button the light on the switch goes off. Any ideas of how to fix or what is wrong?