Due to the fact that Edexcel lost a whole bunch of C3 papers, they needed to release “replacement papers” as the lost ones could have been made available to students unfairly. The replacements were not properly revised. They contained questions not from the syllabus and the questions were much more difficult. The entire set up of the exam had changed as well.
Students are recommended to solve questions from the book endorsed by Edexcel and solve past papers. However, none of those prepared students for this exam.

Edexcel refuses to admit that there is a problem http://inspired-learning.blogspot.com/2013/06/information-for-students-on-edexcel.html?spref=tw

Also, Edexcel centres are so disorganized that some students actually sat for the easier old examination. http://www.bbc.co.uk/news/education-22887009

Generally, Edexcel grade boundaries do change with the level of difficulty, but those generally change only by 2 or 3 marks. This examination will need a much lower curve in order to be as fair as previous years’ exams.

Edexcel has a duty to mark the student’s papers fairly. Students paid and studied for a very hard for an exam that they did not take, but in its place, something that totally discredits Edexcel's name and great reputation.