Mahindra Finance — car key issue

Sir,
I paid full loan amount of ref no:2975163, maruthi 800 at kanhangad, kasaragod, kerala branch on 07.08.2017 i got clearene paper but they don't retern my car spair key when they collect when issuing loan. I ask them they are avoiding. They telling the file keeping kosikode. They don't no anything. Please help me to key back.
Vehicle no: kl 60 g 3839
Model: maruthi 800
Owner name:muhammed kunhi e
Loan no:2975163

Please help, thank-you,