I have the 4.8i and i've had the TSB for the brakes completed in May. Today my brakes quit working properly. I had to mash them to stop the car. It feels like the brake booster isn't working. I've checked fluid level and its fine. Brake pads were replaced about 3k miles ago. Has anyone else had this problem. I've searched and come up empty. Hoping this is something to do with the TSB as I'm out of my extended warranty.