At this point, why not just recall the entire set. I mean now it's 4 discs out of 6 and that's most of the set anyway. All this talk about replacing just discs and how some people are getting a replacement set and some are just getting discs just strikes me as this being a very unorganized process. I would much prefer to just replace the whole set and have them fix everything. Also, if that means the Season season won't be released until next year, than so be it. Just as long as they get it right.
Probably because it's easier and cheaper for them to just mail out the individual discs.
In any case, I'm not too bothered by it. The episodes still play perfectly fine with the alternate audio channel, and the visual effects errors are barely even noticeable.
Doesn't really seem worth getting upset over.