Oh dear he says... Mine does this when its uber cold... and I have my MOT on saturday.... please dnt be screwed calipers!!!!
press the foot brake aswel when the MOT tester shouts ''handbrake on''

a hammer and WD40 free's them up SOMETIMES.
Disconnect your handbrake cables to see if they free up. They could be seized.
I have to leave mine in gear. Dont drive too long with it stuck on. Last time my rear brake nearly caught fire!

Im running mk3 calipers and they have seized. If your looking to upgrade then get mk4 ones