There are two TSBs out for erratic fuel gauges. If it's throwing DTC codes P0546, P008A, P1450, P2196, crank no start - then you need TSB 11-9-3.
If you have horizontal lines on your message center and an erratic fuel gauge, you're looking at TSB 12-1-7.
That said, if you have neither of these and ran out of gas with 1/5 of a tank left, your dealer should be able to recalibrate your gauge. Should.
2012 FF Ti HB Kona Blue, DCT, Built 5/24/2011, 401A + Ti Handling Package, Parking Technology Package, Winter Package, Moonroof, and MFT w/NAV at v3.8 155k miles and counting...