From my limited understanding of your query, I believe you have a weak case for appeal. I would like to extract Section 37 for your easy reference:
(3) Any registered person, who has furnished the details under sub-section (1) for any tax period 8[****], shall, upon discovery of any error or omission therein, rectify such error or omission in such manner as may be prescribed, and shall pay the tax and interest, if any, in case there is a short payment of tax on account of such error or omission, in the return to be furnished for such tax period:
Provided that no rectification of error or omission in respect of the details furnished under sub-section (1) shall be allowed after 9[the thirtieth day of November] following the end of the financial year to which such details pertain, or furnishing of the relevant annual return, whichever is earlier.
1[Provided further that the rectification of error or omission in respect of the details furnished under sub-section (1) shall be allowed after furnishing of the return under section 39 for the month of September, 2018 till the due date for furnishing the details under sub-section (1) for the month of March, 2019 or for the quarter January, 2019 to March, 2019.]
Thus when law itself has provided mechanism for amendment rectify invoices and that amendment has not been made with in such time, remedy in appeal seems difficult. Circular 26/26-2017 GST also discusses various mistakes and suggested rectification.
However you may try writ before High Court. See Y.B. Constructions Pvt Ltd. vs Union of India - 2023 (3) TMI 111 - ORISSA HIGH COURT, where in High Court of Orissa has permitted amendment of GSTR-1 even after time limit is over.