IMO, the lack of protein is more of an issue than the extra calcium. (please, let's not start a calcium war here, folks.) You could boost their protein by giving them an egg, some left over meat. Got any old meat in your freezer? Got any friends who go fishing? Have them bring you their trash fish. But, if I were in your shoes, I'd insist that they give me the feed I was requesting. Friends go the extra mile for friends. It's not too much to ask to get the type of feed you want and need.