Regarding non issuance of share certificates

Dear Sir, My father is a businessman. In 1998 a Association has been formed in the name of wholesale merchants estate limited and they announced to build a trade center and invited all to book their shops in that trade center so my father booked 2 shops and paid money through cheque, nearly 950 members have booked for a shop.Then Association has bought 36 acres of land in the name of wholesale merchants estate limited at that time, but they didn't started the work even after 20 years when we approached them they said we will issue share certificate to all members who booked for a shop but they didn't issued share certificate till now,for the past 6 years they are saying they will issue a share certificate but didn't, I request the experts to suggest what should I do to get the share certificates. Regards, Seenu.