Service tax on sub contractor

Dear Experts, one of our clients is a main contractor in a constructions field he obtained a contract for the value of Rs.1 corer, applicable service tax rate is 4.12% (WCT) . The main contractor gives 60% work to other sub contractors, purely service oriented ie. applicable service tax rate is 10.3%. Now the Main contractor received service tax amount Rs.4,12,000/- but he paid Rs.6,18,000/- to sub contractor. Finally the main contractor Paid excess amount of Rs.3,70,800/- out of his own packet (ie.40,00,000*4.12%=164800 + excess payment to sub contractor 2,06,000/- due to rate variation i.e input is 4.12% out put 10.3%). Is there any provision to avoid excess payment of Rs.3,70,800/-. Please reply with relevant section and/or case law. 

Thanks in advance