Rear brake caliper piston wind back..... Help

Ok so I have been changing my rear disks and fitting new pad this morning, I have managed to changed both the disk, removed the old pads, and put the new pads in place on both sides no issues. Now it came to winding back the piston to allow for the new pads and I have hit a brick wall.

The pistons will not rewind, well one went in a bit and then stopped. I have the laser rewind tool, have removed the brake fluid cap and also released the bleed nipple to try release pressure and still no luck, has anyone got any ideas?

Jake

P.s the handbrake is off and I am going clockwise
 
Sometimes it helps if the nut for pushing the piston is slack I.e. Not pushing the piston back. Try just turning it. I've had problems like you before and simply turning the piston got it to move no bother.
 
Do you need to use a piston rewind tool for the front brakes as well as the rears? As I'm going to be servicing the front calipers and want to make sure I have whats needed as obviously the car wont be able to be used without brakes!
 
Managed to get it sorted about 10mins after my post, got a big 19 mm ratchet spanner on the end of the wind back tool to create a bigger handle and more leverage to really get some force into it. That finally released it and got it going back so it was plain sailing from then. God it was tight tho! Just wished a had though to do that an hour sooner lol.