Hi, I'm having an issue with my brakes. My rear left wheel was making this really loud noise when reversing. Then i started hearing this tingy noise when I was driving forward. Thought it was the brakes and rotors so went for a full change then I noticed this...



Seems as though this thing that's pushing the brake pads in aren't retracting. Does anyone know how I can fix this?

I'm also looking for some bolt replacement, the one that's used to screw the rotor on. Anyone know where I can get this?