Hi, I did mine a month ago...
Bought one on ebay for 100€, came brand new but had to reuse the pulley, no manufacturer listed but its done a few thousand kilometers and works perfectly.
I did not remove the stiffening plate, juste the front plastic tray.
As for the impossible bolt, its doable, using a 13mm flat wrench with a clic mecanism and an articulated head. Something like this :
https://www.mabeo-direct.com/A-48238...AaAiZvEALw_wcB
I did loosen the U metalic hose from the steering rack to gain perfect access even though its tight. The pump comes out from the bottom where the plastic tray sits. all in, around an hour.