The developer mortgages the land rights, then mortgages the projects under construction, and then sells the house to the owner. We paid a down payment, but we couldn't do it because the developer didn't refund the mortgage. Theoretically, pure land mortgage loan has long since ceased to exist. The mortgage of construction in progress can be part or all of the mortgage of commercial housing. If the mortgaged commercial housing is to be sold, the developer must obtain the consent of the mortgagee in advance and cancel it, otherwise it cannot be sold, which also violates the law on mortgage. The local housing management department should monitor the system process.

The buyer signed a house purchase contract without knowing it, and could not guarantee that his interests would not be infringed. Because the procedure is illegal. After knowing it afterwards, it should be terminated immediately: either urge the developer to go through the formalities as soon as possible (cancel the mortgage) or terminate the contract. If both developers can't do it, they can go to the local housing management department to report it, or directly resort to the court.

Your other ideas are unrealistic. Breaking away from the legal track and building a house in a tricky way will lose both sides.