I'd call the mechanic! You paid to have the leak fixed. If you think it's still leaking, it's not fixed. Plus, he sent you out without re-filling the cooling system. If anything, he owes you the anti-freeze.
I am way too picky to trust my car in a stranger. I am concerned about who does what and if something is done wrong, I'd rather it be my fault then fight with someone else.
I take service and quality of service very far (there are two tire shops I will NOT go to in my area because I have been unhappy with them). Heck, the last time I was at the one, the guy working on my '84 Camaro had a pain getting it to stay started! He drove it up (poorly I might add) and insisted numerous times my car had a problem, I need to drive it more and I told him I drive it without fail all the time, I just came here for tires. I finally asked him if he's ever started a car with a carb on it and he quit talking to me and walked away. That was the end of that shop for me.
