Need advice

I have purchased new car from sai cars. They asked me to pay Rs 148000 as down payment. I have paid Total Amount of Rs 148244. I have paid Total Amount of Rs 148244. 1. 10000 initial booking 2. 9000 pawan 3. 56244 chq1 4. 73000 chq2 Receipt I have received Tax invoice :- 581793.00 Tax invoice :- 1000.00 Insurance :- 24456 RTO Passing receipt :- 600 RTO Passing receipt :- 10900 Total :- 618749.00 Total Loan Amount paid to Shreenath Hyundai :- 592980.00 + 148244 ( Down payment) = 741224 Difference :- 741224 -618749 = 122475.00 When I approached them to paid my extra mount they said you will get only rs 30000. They charged me 50000 rs as commission. And give me rs 30142 chq. aforesaid cheque was deposited by me to Bank ,the same was returned unpaid by the Bank with the remarks/reasons "Insufficient Funds". This fact was brought to them notice by me via phone. And even I have not recived my car documents. I called rto person for documents he said sai cars not paid him his charges. Pls advise me about leagal action.