Water wont turn off on my electric shower

[davehayley]

I've had a reliable electric shower (Triton Jade 2) for the last year.
However when i came out the shower this morning and turned the unit off the water continued to keep running. I then tried to turn it off at the pull cord isolation switch but again it didnt work. Theres still power to the shower but the water refuses to stop. At present i've isolated the water at the stopvalve but this means my toilet wont fill with water after i flush the chain. Can anyone help.

Thanks