REVOCATION OF GST REGISTRATION AFTER EXPIRY OF 90 DAYS OR OBTAINING NEW REGISTRATION WITH SAME PAN

GST Registration has been cancelled of my Client on December 2020, After expiry of 90 days when i try to do revocation it is not happening respective authorities are telling that it is not possible and not even the new registration with the same PAN is allowed by them,,, please tell us the process and respective sections