Sad part is that nearly every mid sized city has such a big complex often in the center of the city that is basically an empty shell for a supermarket in the basement.
I mean Karstadt always was the shop, that had plenty of workers running around but you would never get one that knows any of the products. I remember then not being friendly as well. And the insolvency was mostly because bad financial decisions by Schickedanz, which ie Sold buildings to a hedgefond that continuously raised the rents for the properties.