Hmm, that's strange. I usually have no problem getting emergency exit rows in ET and for a LHR-CPT trip in a couple of months my Silver EC card has also allowed me to reserve us supposedly exit-row seats in WT (29 B & C on a 747). No corporate benefits to this trip.

Then again, row 28 is up against the front wall of WT and has certain leg-room / seat recline advantages, and both that row and 29A and 29K are blanked out for me (as are the 'front-wall' seats of 39 and 40), so maybe they simply designate these as 'special' WT seats rather than the emergency exits themselves.