Courier person trying to extort money by bringing police

Hello,everyone courier person is demanding 21000 from me, he brought police constable with him and try to make me culprit and police also taking his side they arrested my father under CrPC Sections 107 & 151 at night from my house and they want 21000 and bribe from me and they are saying that i took courier person product and signed the receipt and returned the empty box to courier person and what happened really is different courier person signed the receipt and took the product and blaming me for this because he have to give 21000 to his company because it is COD order and i can't do anything i don't have the product and police is pressuring to give courier person 21000+ police bribe (asking for 9000),what shall i do now please help me, police want to arrest me under forgery case and try to take me under police remand.