False FIR and chargesheet

Sir, one FIR has been lodged against my father, my cousin and myself u/s 406,420,504,506IPC in july 2015. Nowhere in the FIR time/date even year of offence has been disclosed. He alleges that my father had taken some money to make him a partner in his business but neither made them partner nor returned the money. As proof he has given a receiving on the letter head of our firm signed by my father stating therein,"Received from mrs. Xyz Rs. 13 lac for my personal use." further he alleges that we abused him and threatened by showing pistol. Police recorded our statements that the complainant had given money to us through my real maternal uncle for starting business and later demanded interest in cash. We kept on paying them for 10 years. After failure and closure of business we paid them remaining 5 lac by cheque in 2011. He admits it as well. Now police is filing chargesheet. We said even if we owe them some amount then also its a civil dispute only but they dont listen. What should I do?