You could always make a claim with your insurance company. Just tell them a tree branch fell on the back window while you had it parked outside. That's the ONLY way they will cover it. Pay your deductable and let them pay for the rest including the labor. This way you can tell them you want the glass window also instead of the plastic one. Your claim should not make your rates go up since it was not your fault. They will look at it as a weather related issue.
