GST refund on Cancellation of commercial propery

Hello Team, We have taken a commercial property in Noida through square yards and we made the payments on mar'19 to cyberthum because of negligence of square yards still we didn't get the official agreements from Builder we did lot of followup's we did even expressed our frustration to builder, so he sent agreements in the month of August to square yards but square yards didn't send the agreement copies, last month we finally decided to exit, everyone paid around 10.70L which is 30% of the total amount. One of my group person sent the cancellation papers, finally builder accepted the cancellation but builder sent only 9.58L value cheque's saying remaining amount is deducted for GST. As per my knowledge if a property is registered or gone for agreement then only the Builder can take the GST. So we ask builder to send the GST number and GST invoice against to his property but builder said any GST paid cannot be refunded and said check government rules on GST. can you guys please guide on this.