You didn't bother to give a proper description of what's happening but I guess you mean the water isn't shutting off properly.
If that's the case, there's probably a problem with the solenoid shutoff valve. You MAY be able to repair, but that would assume you can dismantle the valve and clean out any grit in the small bleed hole in the diaphragm.
You may need a new valve - try www.showerdoc.com for parts and more advice - and don't forget to be a bit more forthcoming when describing symptoms
XXX, August 2016
