So I purchased my Corvette new December 2013. In august 2016 my car over heated in stop and go traffic.Car only had 22000 million it. I took it to a Local Chevrolet Dealer, they could not find a problem. They said there were no codes, and suggested i have them purge the coolant system and check for leaks. Well the car pegged out the temp gauge at 260, and blew out a Gallon of coolant and fried the oil, thats the only code I got was 0 oil life and it had only been changed 2 weeks earlier and about 500 miles. Well it did it again in October 2016, so I took it to a different Chevy dealership, once again, they could not find a problem with it? so the last time I took it in it was 2 months away from the bumper to Bumper warranty being expired. They told me at that time if it does it again that it would still be covered because it was a pre existing issue. So yesterday the car did the same thing, I took it to the Chevy Dealership that checked it out last year. So now they want to charge me $135 to Diagnose the problem, I asked why am I having to pay to Diagnose a pre existing issue that you were unable to find the problem. They told me last time if it did it again it would be covered, but they want to me to pay to Diagnose. I did notice last time as I sat waiting for the car to cool down that the electric fan was not on, with the car running or off and coolant was spraying out or the system. Any words oF advice ?