If your car has the aluminium-bodied calipers then the books/workshop manuals say (I believe Haynes and ELSAWIN too) to wind the pistons in clockwise to replace pads etc?
In practice I have found this to be the wrong info?
I found that even using a proper brake piston retraction tool it was a fiddle, as you have to exert pressure on the piston (which of course with the tool makes it want to go clockwise) but at the same time turn the piston (with a big pair of mole grips or waterpump pliers) ANTI-CLOCKWISE.
This is the total opposite of what the printed materials I have so far come across all say, and to all you doubters out there,lol, I've made a written note in my car file that this is the case (I refer to it each time before I work on the car) and has worked both times I have done the job.
The trick is to apply only just enough pressure on the piston to start forcing it back in but at the same time turning it anti-clockwise; if you are really finding that you are applying LOTS of pressure to wind the piston in then something is wrong!
The handbrake mechanism don't forget acts by means of a thread on the back of this piston so don't apply excessive force when trying to get the piston back in, take it easy and it should move slowly but surely.......
Hope this helps!