Caliper bolts stuck on, HELP!!

So went to change the rear brakes on Saturday, drivers side went fine and not a problem.

However came to do the passenger side and the two bolts holding the caliper on to the car are completely stuck, like mega stuck! WD40, bolt releaser, the lot, nothing will get them off. Has anybody had this before and how did you fix it????
 
All I can suggest is more leverage but they can snap making the caliper scrap if the remains are really stuck in there.

Try removing the hose and handbrake cable. You MAY be able to turn the caliper 90 degrees to access the pads with one bolt in place, I can't quite remember what they are like in design.
 
which bolts are you trying to undo?

cant see the 13mm slider bolts being that tight!
 
No the slider bolts are fine, it's the 18mm bolts that hold the bottom part of the caliper on. Need to get it off to change the discs.