Tire wear

I took my car to Monroe for a brake check today, since they were squeaking. Upon getting the diagnosis, besides the brakes, they said my tires on the passenger side have worn, completely uneven, the same wear on both of them, and that the tires have 20 percent left in them. I got the tires replaced in March of 2010, by Monroe. When they put the tires on my car, I got an allignment as well. Today, with the bill for the brakes, they give me a suggestion of an allignment for 80 dollars, and a discount on two new tires. Um, I think something is wrong with this picture. They said that they can't figure out what happened. Shouldn't they at least offer to give me a new allignment for free? I shouldn't be having to buy new tires 9 months later (HRI Fuzions). My car is a 2003 Subaru Legacy. Also, when I left and drove my car later today, it was severely pulling to the left. Thanks