water want stop coming through shower head?

After up rating my water pressure the Triton T80si shower i have will not stop the water pooring through. the only way i can stop it is by shuting the stop valve or stop cock. i have replaced the solienoid which has made no difference. the shower can still not be turned of by the switich. when i open the valve or stop cock the water pours through weather the power is on or off. Can anybody help?