Is it compulsory to Generate Invoice for differential amount

The question here is I have excise duty registration cleared goods only after raising excise invoice only, here my problem is actually the unit price is 33000/- by mistake I raised excise invoice for 30000/- and released the goods, later I found mistake for rectification of erreor shell I raise excise invoice for 3000/- or raise of Debit note for 3000/- is sufficient, pls clarify what is the industrial policy regarding this urgent.

B.V.K.Nageswara Rao