Bad service from GM

My car, which is still under warranty, started misfiring. I took it to GM Johnstone in Kokstad on the 08 August 2017. The Service Manager told me that his workshop was busy/full of cars, so he couldn't help that day. He said the earliest he could open up and see what was wrong with my car was between the 15/16 August. I wanted to take it to another GM in Mthatha, but he advised against it. He also said he couldn't arrange a courtesy car for me because he doesn't know what is the fault with my car. He said it could be my fault. But the Chevrolet Roadside Assistance Programme explicitly states, "Should the Dealership be unable to diagnose and repair your car immediately, you will be assisted with alternative transport (Dealer Courtesy Car subject to availability or alternative vehicle as applicable) or a chauffeur lift, either to your home or planned destination as applicable if within 100 km from your home". None of these were offered to me by the Service Manager. I went and hired a car out of my own pocket. The fault with my car was a broken valve spring, which they fixed under warranty. Now GMSA is refusing to pay me back the money I used to hire the car, while they were trying to figure out was wrong with my car. They are ducking and diving and making all sorts of excuses. I want my money back because the fault was on their side and they should've organized me alternative transport.