Tata Motors — Booked amount not refunded

I have booked a new car for my sister
Tata Tiago XZA+ for an amount 5k.

The total cost was XZA+:-835757 which was an year end offer.

Followed by 5k we have transferred 5lakh and 3.35 lakh rupees to the dealer. Currently I have paid eight lakh fouty thousand in total.which is more than the amount which delear quote.
Once after received the car when I asked the dealers to return the booking amount they were not ready to return it.