CHANGE IN REGISTRATION

I am having a vehicle maintenance busineess (two Wheeler) i am registered under MVAT, my query is i am providing services of  vehicle polishing during this i require some raw material as an input whic i purchase form the unregistered dealer

i raise two bill one is for VAT & the other is for labour charges,

shall is need to Change my registration form reseller to Works Contract

as i am providing material with service

Please Clarify me,

Thanks

Atul