Service tax on educational societies/institutions

vide notification dated 9th september 2013 Educational institutions were exmepted from service tax on certain activities. my specific question is that if a society formed/set up for providing quality education and is registered under section 12 A of the income tax act is getting a new building constructed for educational purpose such as setting up a college and related educational cources. whether the contractor is right in charging service tax on such activity and kindly discuss it in detail the earlier provision i.e position in 2012 and now at present.