From: Rabbi Moshe Sofer
To: Rabbi Yaakov Ehrlich
Members of a community pledged future profits from a business deal to a synagogue building fund; the profits were delivered to the gizbar but later retrieved without rabbinic authorization. The Chasam Sofer rules unequivocally that the money must be returned to the gizbar, as once a neder is fulfilled by delivery to the gizbar, hataras nedarim is categorically impossible. The gizbar bears personal liability if the funds cannot be recovered.
Source: Shu"t Chasam Sofer YD §243