Over laping of Works Contracts with ECI ser etc

Befor Works Contract services in Service Tax Act, if we are giving Service order along with material supply under Errection, commision & Insulation services & Commercial construction services we got abatment of 67% on contract value, service tax paid on 33% @ 12.36% i.e 4.08%.  But as per Works Contract services the rate is 2.06%.  Now ECI & Commercial construction service along with material satisfy the Works Contract service, we are liable 4.08% or 2.06%.  My question is any specific methodology for Separating the ECI, Commercial Construction services along with material and Works Contract Services?  Pls, Urgent Ph: 099891 57666 Email : nageswararao.bommakanti @ ril.com Land Ph: 0884 2388343.