disgusting service received

I purchased a hyundai i30 from the umhlanga branch in 2013. The car was used by the dealership and I am the first owner. I recently noticed rust spots on the roof. I took it to hyundai umhlanga and the response I received was disgusting. They said it was caused by a stone chip it was my fault and and seemed to be irritated by me. The car is less than 3yrs old and under warranty. I took it to an approved hyundai repairer who stated it was not a stone chip but caused by webbing. I called the hyundai dealership and spoke to Marlin and he was again unhelpful and told me to look at my service book. I am disgusted by the service and attitude of the service manager. I know what the warranty says and was informed about this when I was sold the car by Mark Naidoo. My car is still under warranty. I will be lodging a complaint.