Notice u/s 133 (6)

How to reply the income tax notice under sub section (6) of section 133 of Income Tax Act, 1961?

Subject: Calling for information u/s 133(6) of Income Tax Act, 1961 in the case of XYZ.. for A.Y. 2016-17

PAN number is not mentioned on notice as notice is issued by Commissioner of Income Tax of another city, as there is some ongoing case of our XYZ.. customer and we have issued invoice without PAN number. So, they don't know our PAN Number but they have address and contact details.

So, How to reply the notice they want details of invoices which we have issued, closing balance, ITR filed, ledger of party, bank statement etc.