Recovery of GST on cancellation of sale of flat agreement

Customer adv at the time of booking a flat in Project by developer. He also paid GST on that. Now developer has given an option to change to a nre project .Developer agrees to adjust the advance amount to the new project but to refund GST to the customers. Developer can reverse the advance entry and take credit for GST paid. His GST liability gets reduced. He is willing to pass on the above


credit in GST to the customers. is it correct. otherwise what is the best method to recover the GST from developer. Anyo other alternative is available in the above for GST recovery? Will you please advice in the matter.