Sounds like you are going to have to relplace it.......are the pads ok? I ask about the pads only in a last ditch effort....if the piston is having to go too far it might be getting stuck, new pads, not so far to go "out" therefore might not get stuck....as I said a reach.

 

Thankyou for the help... I have new pads. Tomorrow I have to order a Caliper. 300$ here in Norway, and that is an OEM part. woohoo! I have to look at the bright side, I get to learn a bit about my car now

 

Well know that the piston in the caliper "screws" back in.......the new one should not be and issue but one the other side, info to know....but the pads are new.

In the states we can get rebuilt/aftermarket units for less........

 

The shop manual shows how to dismantle & rebuild the caliper. But if you drove with dragging brakes then it's probably seen some pretty high temperatures. I'd go with replacing the caliper.