12.
Dear Querist,
I have noted that you wanted to put subject arguments urgently for filing in the court.
I would strongly suggest you not to do so, considering that facts of your client's case, applicable notification, circular as well as Apex Court ruling - EVERYTHING - are directly against your grounds.
Taking such arguments can be very detrimental for client's case and High Court (assuming that you are talking about writ petition challenging jurisdiction) can even impose cost for raising such frivolous grounds.
Hence, it would be better to defend your client's case both on its merits & time-limitation, instead of challenging jurisdiction of SCN issuing authorities and their adjudication.
These are ex facie views of mine and the same should not be construed as professional advice / suggestion.