Go to Halfords and buy one of these: http://www.halfords.com/motoring/garage-equipment/car-tools/laser-ball-joint-separator-cup
Used it to fit 2x pumps the other day, I have had it since owning a Mini.
I had to use a grinder on both of mine, good luck.
That is on the rear though. Never had any trouble with the fronts.
I got a wiper puller? Are they not the same thing? I tried heating it, spraying it with wd40, used the spanner method, I tried just yanking it off, nothing would budge it