When it starts overfilling, turn off the machine or unplug it and see if the water stops then or not. Also, set the water temps to COLD/COLD and run the main wash.
If it does not stop, it's a valve problem...If it stops when unplugged, its a water level or timer issue. Again, the water level switch only has 3 contacts...get your meter out.
The Performa manual is here on this website.