Share Certificate

It's three years since you purchased the Flat and still Share Certificate not issued?  Clarify whether you are holding a Registered Sale Deed or Agreement to Sale in your favor.

State the facts clearly. why still you are not been provided share certificate?

Any correspondence made with authorities? Why, no action been taken collectively by all members? At least now collectively consult a lawyer and seeking advice and  act according  

First all  have to send legal notice to society for issuing share certificate, if then also they failed to provide you share certificate you can file a complaint to sub registrar of society registration in your jurisdiction.

You can with the support of sale deed subject acceptance of buyer . You disclosed the facts? 

In my understanding, non-issue of share certificate need not inhibit your right to sell your property.

Have you been included as a member of the association, if so, on receipt of the maintenance amount and the corpus funds from you, the association should have issued the share certificate.

Thus you clarify this because you need to obtain NOC from the society for selling the property, without which you may not be permitted to transfer the property to the prospective buyer by a sale deed. 

Sale / purchase of property is a Society (Cooperative Society or Association of flat ) is concerned with "outstanding" against the flat, where the Society withholds NOC for occupation of purchaser.

Otherwise, if you are not a member of the Society it is least concerned with transfer of title (ownership).