Refunds in Housing society's

In 2013 previous flat owner had paid money for installation of shed on the terrace to society. In 2014 he sold the flat to new owner. In 2016 co-operative housing society came to a decision of refunding the excess amount left after installing the shed. Money was not refund to the new owner and neither to the previous owner of the flat . who is the right person to refund the amount or is it to be used my the society itself. What is legally right plz do let me know.