It will take an inspection to know what is leaking, but if the headgasket is leaking, you can continue to have leaks, even after fixing a leak.
In regards to the parts issue, there is a California law about the shop holding on to your parts and being able to supply them to you. Contact the BAR (Bureau of Automotive Repair) for more information.
Have the dealership check the headgasket before making repairs, because if it's leaking it will be a much bigger and more expensive repair than fixing the leak.