What should I do next?

My dad is charged on IPC section 420,406 &120(b). But he has not comitted any crime nither has he supported it. Even there is no evidence against him its just that a person Z gave my dad's name during police investigation that he sold the diamond to my dad. But the person Z himself has got bail. And the main culprits people A,B,C are also out only. We applied for Anticipatory bail on 10/08 afterwhich it got rejected on 16/08. And. They kept my dad in PC then on 21/08 moved him for JC. We again applead for bail it got rejected on 28/08.Then we again applead for bail in session court which got rejected on 1/09. The complainer D had filed his case on 13/07. The police also has no evidence against my dad its just the statement of Z that he sold diamonds to my dad even he does not have any proof for that. But the investigating officer every time tell the judge that the investigation is in process and prays for rejection of my dad's bail so that he could make some recovery. What should we do in such a situation? Please help.. We are stuck completly. And it feels like ki the complainer has bursted the I.O and the P.P. And never has the judgement been placed in our favour. Please help