Asking premium from a member inducted 1 yr. back by Board

Under HIDCO,in HIG,a co-operative housing society with 8 members where land had already been alloted, one of the board members resigned and my father by paying premium to him applied for membership to the society.It was accepted at the board meeting in January2014 by passing a resolution (confirmed by the minutes signed by the chairman),It was also confirmed by the minutes of the AGM in June and even mentioned in the Annual Report as well recommended(both signed by the chairman). I came to know from HIDCO ,that they had been informed by letter about the admission of the new member in February2014. The share and deposit shedule of members as audited ,as on march,2014 mentions my father’s deposit amount and share capital at par with others.(signed by treasurer,chairman & secretary). Now, after one year,one of the board members on behalf of the society is asking for a premium of 25 lakhs for starting the construction of the building.He has convinced other members about the logic.They have put up this demand of premium in minutes of Board meeting in November 2014.According to them the current developed stage has been attained by overcoming many obstacles/uncertainties as a team.Any concession to new member will create disparity among other members. New member is required to pay Rs25 lacs as premium,as the flat value to be constructed is 80 to 85 lacs.If the premium is not paid,they would construct the building with 7 members only and induct new member later.Please advise me what is to be done,and about the legality of this illegal demand which is against the W.B.CO-OPT ACT.