I was asked by a community member the following shailo: A number of years ago he gave a down payment to a frum person who was selling his home. He signed a contract that if the deal fails, he loses the down payment. It turned out, that the deal failed since the banks rejected his loan due to a n investigation against him. The down payment was over 200,000 AUD. The owner sold his home shortly afterward for a much higher amount but refused to return any of the money. Is there any Halachic ground to tell the seller to return some of the money?
On the surface, based on what the person is saying, it sounds like this is the condition that he agreed to. However such a question can only be answered theoretically, until a Rov will hear both sides of the story.