Mark III and AF Seminar
Canon sort of brainwash their staff and come up with documents and seminars on focusing issues often. I remember with my 10d originally I was twice given a lecture on how to focus properly and the limitations. Didn't change the fact that under certain conditions (for me it was with the 24-70 L) the Camera couldn't focus for sh!t. Well I just went ahead and bought a MKII and only ever use the 10d with a 70-200 2.8 IS which it seems to handle pretty well.
Canon are not in the habit of admitting that they screwed up usually and the answer is a training session...typical Japanese style.