Hyundai silverlakes

I took my car in for repairs as the seven year warranty plan is not expired but they are refusing to repair my car saying I don’t have the service book and I bought the car as a second hand 11 months ago, Siyabonga the service manager keeps going around in circles and does not want to assist me,this is the worst customer service ever from Hyundai Silverlakes. I can’t go to work right now because Siyabonga doesn’t want to assist me with my valid warranty.