How to calculate only excise seperately

Dear all,

During Invoice creation we have not calculated Taxes.

and later found that this particular customer belongs to SEZ and now we have to calculate only taxes and send a dr memo

Solution:1 To reverse the Invoice and re-issue invoice with taxes

Solution:2 To pass an adjustment entry and send invoice thru excel sheet, this will not updated excise register. so update in it

I found two possible solutions please share any other solution..

Client don't want to use above two solutions

Naresh