The image you posted does look like classic JPEG corruption, but since the problem doesn't show until RAW processing, that would seem to make it a software interpretation issue, not a hardware repair issue. If it were me, I'd do a couple of things - one is try other process-of-elimination experiments, such as changing the batch process conversion mode, or converting one at a time, etc. The other thing I would do is get with any local camera/photo clubs and find other users who are doing similar processing. There are a lot of Canon DSLR users in those clubs.