You can find the administration of the Studierendenwerk Ulm below the Mensa. The best way to get here is by public transport.
Exit at the bus stop "Universität Süd" (bus lines 3,6,48 and 5).
Walk left past the stairs to the entrance "Uni Süd" and through the glass sliding door.
Open the glass door on the left to enter the Administrative Office of the Studierendenwerk Ulm.