Mine did the same - bought the new front bit see http://www.aqualisa.co.uk/parts-store/Controls/Quartz-Digital-exposed-thermostatic-power-shower/Standard-Controllers/
(after turning off electricity). About £60. Unscrew the screw at the bottom, take out jack/USB thingy, connect jack to new part, screw in and turn on the electricity. It worked! I am no handyman and it was pretty easy and no expensive plumber
J Taylor
May 2010