If a service provider providing Rent a Cab service for which abatement is available at 60% of gross value of taxable value vide notification 1/2006. Can he do the multiple transactions i.e. billing Service Tax at 4.12% where his customers are asking to charge service tax at abated rate. And can he charge Service Tax at full rate i.e. @ 10.30% where his customers are not asking to bill at abated rate of service tax.