Differentiate bill to be raise ?

Dear All,

We sale product with basic price 115,000/-P.M.T but the actual value for the product was 155,000/- P.M.T and they create billing and excise and product has been delivered with low price my client said if there any solution for this to be raise differentiate bill to be raise for example.

ACTUAL BILL AMOUNT –RS  151976/-

BILL SHOULD BE –RS   204838/-

DIFFERENCE AMOUNT –RS-52862/-

i suggested to my client just create a debit note for same with reference of billing invoice then create and also create billing document.

but they said, if we raise debit note we will not get excise payment and they will not release payment to us.

so how can we do it pls suggest me.

Best Regards,

Atul sharma