2004 Chevy Malibu CV joint repair

Does anyone what the average mileage should be before the CV joint would normally need repair or to be replaced? What the cost should be around if the vehicle is taken to a repair shop? Or what the cost of a CV joint would be, if I were to fix it myself?

I was hit by my employer while she was backing out of her driveway. The suspension and strutts were replaced on my car, along with extensive cosmetic damage. Because of the angle she hit my car at, there was quite a bit of damage. I had my car in the shop for almost 2 weeks getting all of that fixed, and when I got my car back, it was making a horrible knocking noi when I turn, especially when I am turning uphill. I took it back, got it checked out and they said it was probably the CV joint. We went over the cost and what not, and my employer's insurance company is only willing to y for a small percentage of what it will cost to get it fixed. However, before my car was hit, I had no problems whatsoever with my car. It was silent as could be. I feel I am being wronged and taken for a ride by the insurance company, along with my employer who isn't exactly stepping up to the plate to assist in paying for costs their insurance isn't paying for. The auto body repair shop said it will cost between $800-$1000 to get fixed, labor included.