We had a similar problem with our Gainsborough 10.5 delux, on a few occasions it just refused to switch off! The water does go cold however (so the element must switch off) and we found that if we turned the temperature right up, the water flow would stop. Then we would wait an hour or so and try to switch it off again, and then it would work. Crazy, I know, but that was it.
Derek
January 2009