Mahindra And Mahindra — cheating with the bill amount

I have purchased a marazzo m2 7seater from eram motors, palakkad, kerala., the quoted amount for comprehensive insurance was 41536 and for music system was 33000 (The dealer offered me a company music system), and i had done the payment accordingly. When i got the car the total insurance amount printed in the insurance is 34000 and the music system was jvc kw - m24bt with for speakers, which cost only 14000 + another 5000 for 2 pairs of speakers. What explanation can you give me for this robbery. I should get a compensation for this.