2 share certificate leading to issue in transfer of flat

In 2004 my father and mother had jointly bought a flat in a co operative housing society. While registering the purchase agreement, the share certificate issued by the promoter to the seller of the property was attached. This certificate was issued in 1992 (No 50 bearing distincy shares from 246 to 250) and was only signed by the chief promoter. However the seller handed over the share certificate (No 32 bearing distinct shares from 406 to 410) which was issued in 1994 by the first office bearers of the society viz Chairman, Secretary and one committee member. We were not aware about this discrepancy until now when we want to sell the flat. The seller is not tracable currently and the present managing committee of the society is not allowing us to transfer the flat on the grounds that we are not the owner of the flat. The society office is in possession of the original copy of share certificate no 50 and we are in possession of the original copy of the share certificate no 32. All the transfer formalities pertaining to name transfer have been done in the share certificate no 32. Also the I & J register mention share certificate no 32 against which our names have been mentioned. I had written an application to the society to issue me a letter stating that the certificate no 32 stands valid along with an indemnity bond indemnifying the society in case any legal issue comes up for the same. The society managing committee didnt accept the application and said i can not transfer the flat as i do not have the original share certificate.