indesit evolution 1000 we 10 wash fault?

this washing machine keeps coming up with the fault F08 on the lcd screen when it is put on a wash above 30 mins i rang indesit and they told me it was the water heater thermostat which i replaced but it did not do the trick.if you persevere with it you can get it to wash but only after switching it on and off 3 or 4times otherwise it just goes to emty when the fault comes up. any ideas