2000 Mercury Mystique All gauges quit working and no chargi

All at once the tach, spedo, and I think the temp and fuel level are stuck in position and no start. Was able to jump start to get to mechanic. Mechanic said to start with battery so it was replaced and then he siad the alternator was bad - replaced alternator. Running but still no gauges. Pocketbook maxed out! HELP! Also this is the 2nd time in a little over two years that I have replaced the battery and alternator both at the same time. Last time dealer did it with provided parts but they also replaced some wiring plug thing near the alternator.