Engine Exhaust System problems of the 2004 Audi S4

I got in my car this past Friday to leave for work and then my car starts rumbling and sounds like what can best be described as a muscle car. I only live a mile from my office so I drive my car in. While driving it seems like the car has lost low end power and is still idling with a rumble. When I get to work I pop the hood and notice the entire motor shifting back and forth and my buddy sees my exhaust is moving up and down. So I decide to get it to the local garage that has worked on my car before. He is only about 2 blocks down from my office. When I pull out from my parking lot the car throws a cel and about 500 ft from the garage it starts flashing. So I coast the car into the garage and get the codes read. They're coming up as cyl. 4, 5, 6, and 7 misfires and p0021 cam timing adjust bank 2 not reached. So the mechanic clears the codes and takes the car around the block and once again the cel comes on and this time it says cyl. 1,3,7, and 8 misfiring and the p0021 code for the cam timing and also a new code p1317 bank 2 cam/crank angle sensor wrong combo of ecu's. . . . To make a long story short the car was towed over 100 miles away to the nearest Audi dealer and was diagnosed as having a faulty cam tensioner. The whole motor needs to be removed and tore apart and the tensioner replaced. The bill is $6286. 18. My car is a 2004 Audi S4 with only 67,000 miles on it and I just purchased it about 5 months ago. It is not under warranty.