my top loader simpson esprit 550 5.5kg won't stop filling?

My washer simpson esprit 550 5.5kg top loader won't stop filling even though it is on the low level. It doesn't matter where on the wash cycle I turn the knob, it just keeps filling.
I have opened the control panel and pushed around in there at all the wiring and turned the machine back on and it has worked fine for 3 complete loads but it has gone back to the filling error.
Can you please help?