i believe 133(6) can only be exercised by taking a prior approval from the commissioner or by the commissioner himself , if no proceedings are pending ., if proceedings are pending AO can issue summons u/s 133(6)
Anyways , information should be provided by you , otherwise it will be a malafide intent . Explain the client the consequences .
sec 132 is sumwhat similar in terms of applicability to sec 147 , and 133(6) is sumwhat similar in terms of applicability to sec 148 .
It should be noted that to prove that your intention is bonafide , information should be provided as asked . Dont sign any documents ( covering letters etc ) in response to summons u/s 133(6) , ask your client to sign it and make him explain all the relevant provisions .
I hope your notes in tax audit report includes that "closing balance of creditors cannot be confirmed as the ......"
Any non submission or wrong submission may lead to sec 272(A) (penalty ), sec 277 ( prosecution ) ..so think twice before you challenge his summons , obviously since this procedure is quasi judicial , show cause will be issued prior to that .