mk1 ford focus, Could this bad rear cylinder be causing my brake foot pedal to the floor? (image included)

Hey, so I have a foot pedal that goes to the floor only when the ignition is on, it is hard when off. i have checked the lines, bled the system 4 times, twice with a air pressure kit and twice the old fashioned two man way. I recently had a guy do the rear brake lines as they needed to be done, he also fitted a new cylinder (must of snapped the bleeder, they were rounded off).

I don't want to have to deal with this guy again, he has not come back for payment, the car is not worth it. but its worth making sure it can stop safely before I move it on. I noticed that the drivers rear wheel does not stop when the pedal is pusher, all others do but when jacked up and brake pedal is pushed, it is free moving.

So I took the dust boot to have a look and found this http://i.imgur.com/KiL5FYW.jpg the brake pedal is pushed (ignition on and off) the cylinder does not move, could this be the cause of the sinking pedal somehow? it bleeds fine and fluid moves through good and no signs of a leak.