You can't move the pedal at all ? Can't feel the free-play ? If so, maybe forcing grease thru the shaft fitting will help. If not, then like Tom said, heat and penetrating oil.
If the pedal still has its free-play, then remove the cover and see if the release bearing will move. If not, pry it loose and very lightly oil the shaft.
The pressure plate fingers shouldn't be frozen, but, let us know if they are.
The plate could be frozen, but, if it were, everything else would probably be working.