Wiring problems of the 2009 Ford Edge

Both tail lights have burned holes through their outer casings. Therefore, when I brake there is no diffusion of the bulb, just the bright light of the bulb shining. Mechanics at my local Ford dealership admitted the problem is caused by faulty wiring, which makes the bulbs burn too hot, resulting in the melting of certain areas of the protective casings. But after informing Ford motor company of the issue, including sending pictures of the damage, I'm still being asked to pay for almost half of the repair; this when I didn't cause the problem and I'm still covered under the extended warranty package of up to 10 years or 100,000 miles. I've reviewed other complaints, and I'm not the first person to deal with this exact issue. Some have had Ford cover the costs, as they should, as it is their equipment that is faulty. But others are in the same boat as me, waiting for the company to take responsibility for their product. As the consumer and a non-car expert, I have no grasp on the range of potential damage or hazard this problem poses. I don't know if burned bulbs and melted casings are the extent of the problem, or if I'm driving around with the chance of a fire looming. I just know I'm dealing with bad wiring, and nothing good comes of that.