Service tax query

Dear Sir,

              i am working in service industry in proprietorship concern or in a security company.  as per govt rules we have to charge only 25% from the service receiver. but, some of our clients have been not registered with the service tax. therefore, they are ready to quit the contract. so, will you suggest me whether i will take full amount of service tax from the service receiver or not. Requesting you to please revert me as early as possible so that i can save my company contract.

Thanks With Regards

Rajiv Verma