Wow. Unbelievable. Here's the worst part: changing your head gasket won't fix that leak! It's literally impossible to tell what seal or gasket is blown, but it's not a head gasket!!! I can't say anything but to tell you that you have a fight ahead of you. To change oil by putting in "the amount you think it should take" is absolutely absurd! Why in the hell does the dipstick exist for then?!? This is why I do my own work, always. I'm a nitpicky SOB about doing things right. I admit that. Dealer shops (no offense) tend to be the worst about things like details. Also, for those that insist on letting others work on your car or even motorcycle, always ALWAYS inspect their work. Sometimes they make mistakes or are lazy or whatever reason, and that can burn up engines or cause accidents. Most dealers or shops make you sign to pick up the car. Guess what? You sign saying you inspected and accept their work!