hero electric - asking for rs 10000 extra for the vehicle

I am currently living in BERHAMPUR, ODISHA. We booked the electric vehicle HERO OPTIMA CX *.* on ** may ****. The dealer told it will take time. So we changed our decision to HERO CX OPTIMA *.* on *th June ****. At that time the on road price of the vehicle was around Rs.****** approx. The same price was being displayed on their website also and there would be a government subsidy(discount) on the on-road price of Rs.******. We paid an advance of Rs. *****. At that time, the dealer told that we will pay ***** at the time of final payment. The battery and charger took a long time to arrive. We went on *nd September **** to bring the vehicle. Till this time, the price of the vehicle is decreased to ***** (on road price). We already paid *****. And the government subsidy is *****. So we should pay Rs. ***** to the dealer. But now, the dealer is telling us to pay Rs.**,*** extra.. We called on the customer support number and emailed them. They did not receive the call. They did not call back. They didn't reply to our mails. There is no response from them. Please help us.. We are a middle class family earning through so much difficulties. Please help...=O=O=O