I'm hoping the jack brigade stands up on this one, it's a necessity imo! If the company can just totally disregard agreements in place as well as the process and promises recently given, then everyone should be completely angered by this as we've basically been duped by their letters....it certainly ruffled my feathers and I support strong action against this.
Wrt to the pension, during my joining process, I was given the documents and had to fill out at home as it requires birth certificates etc so I would use this time wisely to seek council. Incase signing the agreement locks one in or makes it more complicated for the CC to reverse.