Other Fuel System Tank Assembly problems of the 2012 Chevrolet Camaro

I took my car to the dealer with a fluid leak at th passenger rear side of the car. . It was very minor, producing only a small "baseball" sized stain in my driveway over a 3 month period. Fluid was greasy and sticky. The dealer reported that the clamp for the filler tub was not properly installed but rhe factory. They said they repaired it by removing and reclamping it on. Once I returned home with the car, I had a whole new problem. Gas now leaks out on my driveway anytime the tank is above one-fourth full. The fluid on the driveway is distinctly gas, whereas before, it did not have the odor or appearance of gas. It was sticky, more tacky like a grease. I returned to the Chevrolet dealership and they informed me that I have a cracked gas tank. They will not admit that they inadvertently cracked it during the previous repair. This only leads me to believe that Chevrolet has an inherent issue with their gas tanks in that they will crack without cause by the driver. This car was a certified pre-owned Chevrolet. It had approximately 23,200 miles on it al the time and the warranty had expired due to timing: the 24 months was over in April 2018. The "cracked" gas tank was discovered in August. Please review. This is a safety issue and could result in injury or death to the occupants of the vehicle.