Water leaking from Shower Unit?

I have a Triton T80si ekectric shower, over 2 years old.
The water is escaping from the shower unit attached to the wall tiles.
Upon further inspection the water is leaking from the part called "Stabiliser valve assembly"..located above the water inlet.
Is this value repairable or do I need to purchase a new part?
thanks

Mark W
June 2005