Although pricier, the CAT shuttle is a faster, direct transfer to Wien Mitte (Landstraße) with no stops along the way. (Same route with S7)
Once you are at Karlsplatz metro station, follow the “Opernring” exit, you can find our building (Opernring 1) right on your left side (across the Opera). Our office is in building E, 6th floor. (The leftmost lift) room 633.