I had this same "it's a fast lens so it will have CA" discussion a few weeks ago on this forum and did post a quick sample of a high contrast file and 100% crops of center and corners straight out-of-camera showing absolutely zero CA or purple fringing. Just search my posts and you should find it.
Worth repeating .. a well tuned 135L shows ZERO CA OR PF under any lighting conditions.
Well, those posts must have been made longer than four weeks ago, because I've yet to find them when I search.
This is somewhat the first I've heard of the 135L having trouble with PF. Canon might be able to do some adjusting for you, but unless the lens is an apo-chromatic lens, there isn't a guarantee that the PF will be completely eliminated.