You may have already tried looking for the Mirror's Edge DLC today with no luck and here's the reason why: it wont come out until sometime next month!

According to website Bigdownload.com the EA spokesperson they spoke with had this to say

To offer a completely smooth experience for players, DICE announced today that the DLC map pack for Mirror's Edge on the Xbox 360, PlayStation 3 and PC will be delayed until February. However, the free exclusive map for PlayStation 3 players will be available to download on January 29 as previously announced.






Although I'm not sure how "smooth" it is to say you will release something and then just not do it and only let people know one day before it happens, I think that qualifies as "unsmooth." Either way, you will have to wait longer for the Time Trial DLC, sorry about your luck!