Payment for flat sale to society

I have sold a flat in Thane in July of this year. The society was not registered at that time.... The society was registered in Nov this year and now the society is asking for 30000 for transfer of deeds to the new owner. I never got any share certificates for the society and I also had got a NoC from the builder for the sale of the flat. Is the society that didnt exist at the time of sale withinh its rights to ask for such a payment

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