Mahindra First Choice [MFCWL] — mfc, mukesh auto kalikapur, kolkata holding back my rc book inspite of all amount paid

Address:

Kolkata, West Bengal, 700096

I purchased WagonR (WB74M - 7973) car on May 2017. I have paid the entire amount including Rs. 18000 for Name Transfer which is clearly mentioned in the Cost Sheet duly signed and stamped by their Executive. When I visited them on 11.07.18 to enquire about the status of my RC Book, they said the Name Transfer is done by I need to pay Rs. 8000/- more towards Name Transfer else they will not handover me my RC Book. I tried to reason out that I have already paid the entire amount but they refuse to budge. I was not even informed even once during the entire process of Name Transfer that i need to pay extra for the same. Moreover the additional amount being demanded violates the agreed amount as mentioned in the Cost Sheet.
I request you to kindly resolve the issue at the earliest