It does seem like it's getting trickier to get to Poland, even more than before, and also more difficult in general to get a Schengen visa (to any country). Did your friends try entering Poland by car, train or air from the Czech Republic? I totally understand the risk of making all those arrangements, paying for tickets and hotels in advance - only to be denied at the border.
It has been discussed over and over what to do in this situation, and I wonder what happened to some of the people who came on here looking for help but never came back to say whether they found a way out or not. I never contacted my Congressional rep for intervention in my wife's case, but sometimes that is the way out, if you have a good rep I guess. It has also been suggested to write a joint letter to the Bureau of Consular Affairs, but in the end there has to be an embassy with the ability to take on cases. There have been isolated cases of embassies taking transfers without requiring residency, but they seem few and far between and not any one in particular stands out as consistently taking transfers - except for Jerusalem, which is not taking new transfers apparently. Jerusalem accepted our transfer on the basis of having a Schengen that we couldn't really use to get to Poland (Greece's explicit conditions). I also explained that our case was simple document-wise (U.S. citizen kids, no previous marriages, no criminal record, etc).