Threatening of being jailed under false dowry case

Sir, my elder brother and his fiancee broke their marriage after engagement under mutual understanding. Now the family of the girl is asking for a hefty amount for compensation against expenses incurred in engagement (which we have cross checked with the banquet owner is a falsely quoted amount). They are threatening my family that if won't pay them the amount they will book us under Dowry act and will get my entire family jailed .The uncle of the girl threatened us that he is a magistrate and all he get my entire family jailed. No dowry was demanded ever.Instead we gifted girl gold ornaments.