Recreational Vehicle Lpg Tank Valve/gauge problems of the 2012 Kia Motor Optima

I have a 2012 kia Optima hybrid of which I purchased at the local kia dealer (ontario, CA) and even purchased an additional "platinum 100k mile protection. " on December 31st my car started to move while in park and the ignition on. I hit the breaks and there was no break pressure at all. The car started to flash codes regarding the brakes and I had to engage the emergency break to stop the vehicle. The dealer could not find the issue and returned the car. Another month later the car did the same thing and I video taped it. The gauges started illuminating and delluminating repeatedly and all the lights on the dash started to flash. The "check brake" code came up again! I now have proof of the vehicle doing this and brought my car back to the dealer now they have admitted something is wrong but they're still unable to duplicate the error. They are keeping the car for further diagnosis but have not done anything but tell me they do not know what is wrong with it yet and that my warranty "may not" cover it. They have told me repeatedly that they will not be able to fix it or do anything for me until they know what is wrong, nor have they offered me a rental car. I want my car back but it is unsafe! what if the brakes go out at a high rate of speed?! please hep me NHTSA so we can save lives of others that may experience this problem as well.

Tl-the contact owns a 2012 kia Optima equipped with hankook, tire line: optimo h431, and tires size 225/45/r18 tires. The contact stated that while driving 20 mph, the tire gauge light illuminated. The contact took the vehicle to an independent mechanic. The mechanic stated that the rear driver's side tire had an air bubble. The tire was not replaced. The manufacturer was not notified of the failure. The VIN was unavailable. The approximate vehicle failure mileage was 36,000 and the tire failure mileage was 7,000. The dot number was not available. Cs.