I have to direct my outrage at the fact that my chapter doesn't work at something, and MS is so faceless it wouldn't make me feel any better.
Just be happy they offered to put it up in the first place. They don't owe you a thing and it's a great gesture. Being angry because it'll be a few days late (especially towards the people who did you such a huge favour in the first place for no cost) is extremely childish and ungrateful.
I'm not saying you are that, but if it is the case, it's a silly attitude to have. How would you take it if you did something really nice for someone for no reward and they then started shouting at you because your gift was slightly late? Personally, i'd completely take it back.