Thanks to forum member 850Rick, I have a working s/hand one on it's way, and have ordered a removal tool from amazon, so fingers crossed that it be fixed sometime in the next few days.
If it gets it sorted for the time being, I guess I had better save up for a new genuine one at god knows how much, hundred quid or so I believe
Can a small trace of copper slip be used to prevent future seizing?
Also, I understand a good blast of wd40 before undoing the old one would be a wise move?