STRIPPING OF ENTIRE MOTOR ENGINE

I recently took my Chev Captiva to CME for a broken Cambelt Tensioner, which resulted in damage to my engine head and some bended valves. I made contact with CME and explained exactly what the issue was and requested a quote to repair the necessary damage. After two weeks of follow ups I eventually got a quote back, where I was informed that the vehicle needs a total engine overhaul, Cost R76k. Knowing that that wasn't the case I requested the vehicle to be towed back to my house. It as now come to our attention that CME stripped my entire engine (which wasn't my instruction) and left all the parts in the back of my vehicle. The took out my entire gearbox and also stripped my air-conditioning system. These unauthorized actions by CME have now resulted in further costs, such as gassing of the aircon, re-attaching the entire vehicle mechanisms. On top of that I had to pay them a stripping fee. They also advertise that they do the necessary research to get the best part prices. It seems that they only manage to find parts from the tactual Chev supplier. I easily manage to find cheaper parts.Why couldn't they just quote me for the actual damage parts?