When Braking at 30-35 mph the car pulls to the left

The following has been replaced by a reputable mechanic:
front pads
rotors turned
both calipers
master cylinder
both brake lines
front end alignment
everything visually inspected and tight

It pulled real hard before this stuff was done at all speeds and now it pulls a little at around 30-35 mph. I have read many things and I asked my mechanic if they checked the front end and they stated that everything is tight and looked good. I just perchased the car and this started a week later. The car also newer tires on the front and the rear is about half worn. My mechanic stated on the receipt that this was the best that they can do. I would appreciate your professional opinion. I don't know what to do next as I have spent a lot of money already.