How to quash illegal & invalid transfer of membership wrongly made by the CHS.

X(seller) sold the flat to Y(purchaser) in June 1989 and Y submitted all the documents and agreement to the society situated in Mumbai, Maharashtra, for transfer of membership in the name of Y.  Agreement submitted to the society was unregistered and unstamped, still the society transferred the membership in the name of Y(purchaser) in June 1989. The possession of the flat was not given to Y, since the consideration amount was not paid by Y(purchaser) and the possession always remained with X(seller).   To resolve the issue amicably, both the original executants mutually decided to execute the Deed of Cancellation and it was executed in Dec 2018. During the legal consultation X(seller) came to know that the transfer made by the society in the name of Y(purchaser) is invalid and illegal since the transfer of membership was done on the basis of an unregistered and unstamped document (Section 53A of Transfer of Property Act). Please note that my case is just a "case of revocation of illegal & invalid membership wrongly transferred by the society." Now X(seller) wants to quash/void the wrong transfer of membership made by CHS and transfer back the membership in the name of X(seller), the original member of the society".