Fwiw I can see no reason why a previous garage would have felt it necessary to remove the
oil filter housing when replacing a water pump.
Besides which, if the damage had been done at the beginning of March you would have noticed the puddle of spilt
power steering fluid then & not straight after this servicing.
The plastic
oil filter housing has clearly been chewed up by someone trying to use the type of tool that is generally used on metal cartridge filters. Those tools do not grip the plastic housings, and it is easy to envisage someone attempting to remove your plastic housing with the wrong tool and slipping whilst applying considerable force in an attempt to make that wrong tool grip. Your
power steering header tank lies precisely where you may expect the slipped tool to impact.
Imho they owe you a filter housing as well as the
power steering tank.
Fyi the correct type of tool for removing your type of filter housing is like this.:
https://www.amazon.co.uk/gp/product/B07FVN7X2V/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1
As a guess, based on the damage, they probably tried to use something like this.:
https://www.amazon.co.uk/Draper-77592-Filter-Wrench-130mm/dp/B0001KA1YO/ref=sr_1_15?crid=13UKYFM0BYUM7&keywords=oil+filter+removal+tool&qid=1683737480&s=diy&sprefix=oil+filter+removal+tool,diy,574&sr=1-15
Hth