The story of these brakes is that I bought them as a christmas present to myself for my mountain bike. *Note* I am very happy with them and the only reason they're underperforming is because I know that either the pressure is low or that there's air in them (actually it's just the front - the rear brake feels perfect).

I'm guessing the problem is because the amount of fluid is low, because the front recently leaked. Why did it leak? The mech who installed them apparently did not tighten one of the hoses properly (I normally like doing the work myself, but these were my first hydraulic brakes, and I didn't want to possibly mess something up) and a small amount of fluid came out during a recent ride.

The thing that bothers me is that, although he admitted to the mistake, he insisted that it felt the same as the rear brake (it absolutely doesn't, the rear lever feels firm and strong; the front feels, like I said, spongy and weak.)

I felt like I rambled so the question is: what is the actual problem with my front brake and what should I say if the mech says that he doesn't feel a difference again? (I have a feeling I know the answer to this).