How do I know my car has a cracked head? on 2002 Mercedes-Benz C230

I had the head gasket changed, as well as the thermostat. There has been no definitive test as to why I am losing coolant. The dealer had my car for a week, and they tell me "it must be a cracked head. We can't really determine for sure until we open up the head". I don't understand the answer, as they should have seen this when they changed the head gasket? Pressure tests show nothing. I am losing coolant still.

Asked by for the 2002 Mercedes-Benz C230
This should have been checked before replacing the head gasket by either the repair shop or by sending the cylinder head to a machine shop. standard proceedure when replacing a head gasket.
Wow...I thought so. This is a major Mercedes Benz dealer in the area. Can you suggest what I should do?
Not very professional of them,I would try to go after them legally but first i would try calling mercedes benz usa corporate office, they might go after the dealership. good luck.

F&M Tire & Auto Service
1 more answer , 1 more comment
the head should have been sent out and check for cracks and warpage
Thanks for the reply..when I first brought the car into the dealer- they used a scope to determine that the head gasket was cracked. I asked if the heads were ok, and they said yes. Now I am told it isn't. Does this sound like an irresponsible repair? I just want my car fixed.