You have to use the open end till you can move it around some. I don't have any of the bi'direction type wrenches. mostly I reach under the pump and up.
a whole lot of force is not needed, especially if you set up some vibration with a 'tap'.
2 prong puller sort of like this
![](http://www.acmachining.com/wp-content/uploads/wp-checkout/images/tdi-cam-gear-puller.jpg)
I made one from a picture online, but don't recall seeing the actual VW tool. mine is 2 large bolts with ground down heads that are put through the pulley holes, and rotated to lock, then the force screw is turned.
I can't find the picture now.