no sound from the radio or sync system

I first noticed the radio problems when the volume control was acting like it was possessed. I tried turning the volume down and it stayed put for a few seconds before adjusting. Over the course of the week the problem got worse, I could turn it up all the way, or down all the way and it would freeze. One one occasion I had no volume so I adjusted it to max with nothing, then turned it back down. Out of nowhere it blasted for a good 10 seconds at max volume before I had to turn the radio off to avoid blowing out my eardrums. I have lost the ability to use the sync system because there is no volume. At this point my radio does not even work. If I leave it on I will get a random 5 second song lyric every now and then. I have an appointment with the dealership Thursday because not only it this annoying, but I am worried there is an underlying electrical problem that may cause a serious accident.