Vehicle stolen and fir lodged

My vehicle (lorry) was stolen from the highway dhaba when the driver left to bring the mechanic for some minor repair. I have lodged a police complaint and in FIR it was mentioned that the vehicle was stolen and the police office has taken the statements from the witnesses. Now, the police officer called me and said that he has changed the statement in FIR saying that it was a false complaint. he said that while investigating he has found nothing. I have taken loan on that vehicle and I have also informed that person about the theft. Now, the police has changed their statement because of the influence of that creditor who gave me the loan on that vehicle. I request you to please guide me on this matter. whether I have to withdraw the case I have filed or to continue to prove that the vehicle which was stolen. What the creditor can do? Can I go against the police for doing improper investigation and making a report that the vehicle was not stolen? How could I prove in the court of law that the vehicle was stolen? Please, I request you to guide me on these matters. Thanks, Rizwan